Unit 20: Earth Science

Introduction

Tuesday September 3, 2013

We’re about to dive into a comprehensive course that teaches the big ideas behind rocks, minerals, and the science of geology. Soon you’ll learn how to burn coal, fluoresce minerals, chemically react rocks, streak powders, scratch glass, and play with atomic bonds as they learn how to be a real field geologist.

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Everything is matter. Well, except for energy, but that’s everything else. Everything you can touch and feel is matter. It is made up of solid (kind of) atoms that combine and form in different ways to create light poles, swimming pools, poodles, Jell-O and even the smell coming from your pizza.

All matter is made of atoms. Shoes, air, watermelons, milk, wombats, you, everything is made of atoms. Hundreds and billions and zillions of atoms make up everything. When you fly your kite, it’s atoms moving against the kite that keep it in the air. When you float in a boat, it’s atoms under your boat holding it up.

My definition of an atom is: the smallest part of stable matter. There are things smaller than an atom, but they are unstable and can’t be around for long on their own. Atoms are very stable and can be around for long periods of time. Atoms rarely hang out on their own, though. They are outgoing and usually love to get together in groups. These groups of atoms are called molecules. A molecule can be made of anywhere from two atoms to millions of atoms. Together these atoms make absolutely everything, including the minerals, crystals, and rocks we’re about to study.

A periodic chart has a bunch of boxes. Each box represents one element. In each box is a ton of information about each element. All atoms are made from the same stuff; it’s just the amount of stuff that makes the atoms behave the way they do.

If you look at a periodic table you will notice that there will be about 112 to 118 different elements (this will vary depending on how recently the table was created). About 90 of those occur naturally in the universe. The other ones have been man-made and are very unstable. So imagine: Everything in existence, in the entire universe, is made of one or several of only about 90 different types of atoms. Everything, from pianos to pistachios are made from the same set of 90 different Legos!

Now, if you find that amazing, listen to this: Almost everything in the universe is mostly made of only twelve different kinds of atoms! But wait, there’s more.

All living things are mostly made of only five different kinds of atoms! Five! You and a hamster are made of the same stuff! All living and once-living things are made mostly of carbon, hydrogen, oxygen, nitrogen, and calcium. Ta daa! Those are the ingredients for life. Put ‘em in a bowl, stir and voila, you can make your own penguin.

Okay, obviously it’s not that easy. It takes a lot more than that to make life, but at least now you know the ingredients. An easy way to remember the main ingredients for living things is to remember the word CHONC. Each letter in CHONC is the first letter in the 5 elements carbon, hydrogen, oxygen, nitrogen and calcium.

One last interesting thing to think about here: Of all the atoms in the entire universe, 90% of them are hydrogen. Only 10% of the entire universe is made up of anything other than hydrogen.

Throughout this course, we’re going to be talking about the chemical composition (what elements rocks are made of), so you’ll really understand chemistry and geology both!

Minerals are pure chemical substances, made up entirely of one molecule through and through. Examples of minerals are everywhere. Rock salt is a mineral called halite. Fool’s gold is a mineral called pyrite. They are made of a single substance and nothing else. Rocks are composed of two or more minerals. We’re going to study rocks, minerals, crystals, and more in our unit on geology!

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Color Streak

Tuesday September 3, 2013

You will be able to identify minerals by their colors and streaks, and be able to tell a sample of real gold from the fake look-alike called pyrite.

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Materials

1 handheld magnifying lens
Unglazed porcelain tile
Rock samples (the ones in the video are: graphite, pyrite, talc, iron, and jasper)

Download worksheet and exercises

Every mineral has a set of unique characteristics that geologists use to test and identify them. Some of those tests include looking at the color of the surface, seeing if the mineral is attracted to a magnet, dripping weak acids on the rock to see if they chemically react, exposing them to different wavelengths of light to see how they respond, scratching the rocks with different kinds of materials to see which is harder, and many more. There are more than 2,000 different types of minerals and each is unique. Some are very hard like diamonds, others come in every color of the rainbow, like quartz and calcite, and others are very brittle like sulfur.

The color test is as simple as it sounds: Geologists look at the color and record it along with the identification number they’ve assigned to their mineral or rock. They also note if the color comes off in their hands (like hematite). This works well for minerals that are all one color, but it’s tricky for multi-colored minerals. For example, azurite is always blue no matter where you look. But quartz can be colorless, purple, rose, smoky, milky, and citrine (yellow).

Also, some minerals look different on the surface, but are really the same chemical composition. For example, calcite comes in many different colors, so surface color isn’t always the best way to tell which mineral is which. So geologists also use a “streak test”.

For a streak test, a mineral is used like a pencil and scratched across the surface of a ceramic tile (called a streak plate). The mineral makes a color that is unique for that mineral. For example, pink calcite and white calcite both leave the same color streak, as does hematite that comes in metallic silvery gray color and also deep red. This works because when the mineral, when scratched, is ground into a powder. All varieties of a given mineral have the same color streak, even if their surface colors vary. For example, hematite exists in two very different colors when dug up, but both varieties will leave a red streak. Pyrite, which looks a lot like real gold, leaves a black streak, while gold will leave a golden streak.

The tile is rough, hard, and white so it shows colors well. However, some minerals are harder than the mineral plate, like quartz and topaz, and you’ll just get a scratch on the plate, not a streak.

Number your rock samples by placing them on your data table.
Using your data table, record the color of each sample.
Now use your streak plate. Take a rock and draw a short line across your streak plate (unglazed porcelain tile).
Record the color of the streak in your data table. Are there any surprises?

Exercises

What does it mean if there’s no streak left?
Give an example of a kind of rock that leaves a streak a different color than its surface color.
What is a mineral that appears in two different colors, yet leaves the same color streak?

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Mohs’ Hardness

Tuesday September 3, 2013

By the end of this lab, you will be able to line up rocks according to how hard they are by using a specific scale. The scale goes from 1 to 10, with 10 being the hardest minerals.
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Materials

Steel nail
Penny
Small plate of glass (optional)
Rock samples (minerals in the video: talc, selenite, calcite, fluorite, apatite, feldspar, quartz)

Download worksheet and exercises

The sample’s hardness is determined by trying to scratch and be scratched by known materials, like pennies, steel, glass, and so forth. If the material leaves a mark on the mineral, then we know that the material is harder than the mineral is. We first start with a fingernail since it’s easy to use and very accessible. If it leaves a mark, that means that your fingernail is harder than the mineral and you know it’s pretty soft. Talc is one of the softest minerals, making it easy to scratch with your fingernail.

However, most minerals can’t be scratched with a fingernail, so we can try other objects, like copper pennies (which have a hardness of 2.5-3.5), steel nail (3.5-5.5), steel knife (5.5), and even quartz (7). The most difficult part of this experiment is keeping track of everything, so it’s a great opportunity to practice going slowly and recording your observations for each sample as you go along.

Number your samples on the data table and place each rock on the table. If you have the same samples listed above, you can scratch each rock with every other rock to find where they are on the Mohs’ Hardness Scale, where 1 is the softest and 10 is the hardest:
Mohs’ Scale of Hardness Talc
1. Selenite
2. Calcite
3. Fluorite
4. Apatite
5. Feldspar
6. Quartz
7. Topaz
8. Corundum
9. Diamond
If you don’t have one of each from the following scale (at least up to quartz), then you’ll need to do this experiment a different way – the way most geologists do it in the field. Here’s how:
Scratch one of the rocks with your fingernail. If you can leave a mark, then write “Y” in the second column of the data table. Now skip over to the last column and estimate the hardness to be less than 2.5.
If you can’t scratch it with your fingernail, try using the mineral to scratch a copper penny. If it doesn’t leave a mark on the penny, skip over to the last column and estimate the hardness to be between 2.5-3.5.
If it does leave a scratch on the penny, then try scratching the mineral with a steel nail. If the nail leaves a scratch, skip over to the last column and estimate the hardness between 3.5-5.5.
If you can’t scratch the sample with the nail, see if the mineral can make a scratch on the plate glass. Glass has a hardness of 6-7. If it doesn’t make a scratch on the glass, then it’s between 5.5-6.5. If it does, it’s higher than 6.5. For example quartz will make a scratch on the plate, and its hardness has been recorded at 7.

Exercises

If a mineral scratches a penny but doesn’t get scratched by a nail, can you approximate its hardness?
Give examples of the hardest and softest minerals on the Mohs’ Scale.
Is feldspar harder or softer than quartz?

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Cleavage & Fracture

Tuesday September 3, 2013

Today, you’ll learn what to look for in a broken mineral. There are different names for the types of breaks that a mineral can experience. You’ll need to ask a few important questions during your investigation, like, “What is the difference between mineral cleavage and fracture?”

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Materials

Mineral samples
Hand lens
Good lighting

Download worksheet and exercises

Cleavage and fractures are two properties that geologists test at the same time, both by observations. Using a hammer, geologists will break a mineral by studying how the mineral broke. They describe the way the surfaces look. Sometimes minerals break apart like they were stacked together in thin sheets. Other times they break off in large chunks, and the sides of each chunk are always at right angles. The way that they break into planes is called “cleavage.” Minerals can have cleavage in one direction, like mica, or two or three directions (like halite). The type of cleavage is also described using geometric terms. Halite has cubic cleavage because when it breaks, it looks like it’s made up of tiny cubes, while calcite has rhombic cleavage because it never breaks into right angles, but always in a rhombus, or diamond shape.

Fracture describes the surfaces that are broken but don’t break along plane lines. A mineral can have both cleavage and fracture, and some have either one or the other. Quartz has no cleavage, only fracture. Calcite has no fracture, only cleavage. Feldspar has both.

Geologist look for smooth surfaces, which can be (when viewed up close) cubes, triangles, or simple, flat plane surfaces. Always look for cleavage first, then fracture when making your data observations.

An easy way to look for cleavage is to hold the sample in sunlight and look for surfaces that reflect light and describe the surface in one of three ways for cleavage:

Perfect – the mineral breaks to reflect a clear, glass, or mirror-smooth surface.
Good – the mineral breaks to reveal a surface that reflects light, but may be dull in places.
Poor – the mineral breaks along clear planes and flat spaces are visible, but these are dull and could be ragged, and not very reflective.

Remember, a mineral can have more than one cleavage plane. For example, feldspar has two cleavages, one which is perfect and one which ranges from poor to good, depending on the sample. At first glance, you might not be able to tell feldspar from quartz, but if you look for cleavage, you’ll find feldspar has two planes of cleavage whereas quartz has none. Quartz will look like lots of broken surfaces that are not flat planes.

The way a mineral breaks depends on what the crystalline structure looks like. Here are some forms of cleavage:

Basal cleavage is cleavage on the horizontal plane, like mica. Basal cleavage samples can sometimes have their layers peeled away.
Cubic cleavage is found in mineral that have crystals that look like cubes., like with galena or halite.
Octahedral cleavage is found on crystals that have eight-sided crystals, like two pyramids with their bases stuck together. Look for flat, triangular wedges that peel off an octahedron, like in the mineral fluorite.
Prismatic cleavage is found in minerals that have four or more sides and are long in one direction, like aegirine, where the crystal cleaves on the vertical plane.
Rhombohedral cleavage is really my favorite, because it shows up in calcite so well due to its internal crystal structure, which is made up of hexagonal crystals. No matter where you look, there are no right angles to this cleavage – everything is at an angle.

Fracture can be described like this:

Conchoidal (like a shell, for example: obsidian)
Earthy (looks like freshly broken soil, like limonite)
Hackly or jagged (when a mineral is torn, like with naturally occurring silver or copper)
Splintery (looks like sharp, long fibrous points, like chrysolite)
Uneven (rough surface with random irregularities, like pyrite and magnetite)
Even or smooth (the fracture forms a smooth surface)

You will begin by labeling each of the mineral samples, starting with 1. Make sure to keep track of these samples throughout the entire lab.
Take the mineral samples and note which number it is on your observation data sheet.
Using your hand lens, look carefully for little sparkles of surfaces that reflect light. These are the cleavage surfaces.
In the space marked cleavage on your worksheet, label the cleavage as perfect, good, or poor. If there are no flat surfaces that are broken, write “none.” Some of your samples may have more than one cleavage. Make a note if this is the case.
Now look for broken surfaces that are not flat. Place a check below the best category of fracture that the mineral shows. If there are no surfaces like this, mark “none.” If you are uncertain about either category, leave the section blank. It is better to record no information than to mark something that can mess up your data.

Exercises

Which properties do geologists look for when they try to categorize a mineral? Circle all that apply.
1. Color
2. Shine
3. Smell
4. How it breaks
If you break a sample of quartz and find that it has no clean surfaces of separation, what kind of cleavage does it show?
True or false: A mineral can show more than one type of cleavage or fracture.
What is a fracture called that is similar to glass?

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Acid Test

Tuesday September 3, 2013

Your goal is to identify samples according to their reactivity with acid. Minerals that react are called chemical rocks, and minerals that don’t are called clastic rocks. Some chemical rocks contain carbonate minerals, like limestone, dolomite, and marble which react with the acid.
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Materials

Acetic acid (plain distilled white vinegar) in a dropper bottle or in a small cup with a medicine dropper
Pie tin
Paper towels
Steel nail
Optional: handheld magnifier
Rock samples (in the video: bituminous coal, limestone, conglomerate, coquina, shale, siltstone, sandstone, and dolomite)

Download worksheet and exercises

If your sample fizzed, you’ve got carbonate in your sample, and your sample might be calcite, marble, coquina, or limestone. If the powder fizzed, you’ve probably found dolomite, which is similar to calcite except it also has magnesium, which bonds more tightly than calcium, making the sample less reactive than limestone.

The reaction doesn’t always occur quickly. Sometimes you’ve got to be patient and wait. For example, magnesite has a weak reaction with acid, and if you grind it to a powder and then test, you have to wait half a minute for tiny bubbles to form. Magnifiers are helpful for these smaller, weaker reactions.

A lot of rocks contain small amounts of calcite or other carbonate minerals, so all of these make a fizz even though carbonate is only a small part of the rock. There might be small veins or crystals of carbonate minerals that you can’t even see, yet when you place a drop of acid on them, they bubble up. You can tell these types of rocks from the real thing because you won’t be able to do more than one acid test on them. The second time you try to add a drop of acid, there will be no reaction. The acid test is just one of many tests used, and shouldn’t be the only one that you use to determine your sample’s identification.

Chemically speaking, when you add the acid to the samples, you’re dissolving the calcium in the samples and releasing carbon dioxide gas into the air (these are the bubbles you see during the reaction).

For calcium carbonate and vinegar, the reaction looks like this:

2CH3COOH + CaCO3 → Ca(CH3COO)2 + H2O + CO2

The first term on the left CH3COOH is the acetic acid (vinegar), and the second term CaCO3 is the calcium carbonate. They both combine to give water H2O, carbon dioxide CO2, and calcium acetate Ca(CH3COO)2.

Carbonate minerals that react with acid (either vinegar or hydrochloric acid (HCl) as shown in the video) include aragonite, azurite, calcite, dolomite, magnesite, malachite, rhodochrosite, siderite, smithsonite, strontianite, and witherite. You can increase the reactivity with HCl by warming the HCl solution before using for the acid test.

You can do this experiment in other ways, too! Place a piece of chalk in a cup of vinegar and watch the tiny bubbles form on the chalk. This also works for egg shells, because they also contains calcium.

Do not let kids test their minerals with hydrochloric acid.

(For teachers demonstrating the HCl version of this test: CaCO3 + 2HCl → Ca++ + 2Cl–+ H2O + CO2)

Note: a few rocks, like coquina, oolite, and tufa can produce an extreme reaction with hydrochloric acid because they have a lot of calcite, and/or a lot of pore space that allows for high surface areas (exposing more of the calcium carbonate to the acid). The reaction will be quick, foamy, and vigorous, which is why we only use one drop of acid at a time.

Number and label your samples using the data table.
Use a dropper to take vinegar out of its bottle.
Drop a few drops onto your sample and watch for a reaction. You’re looking for bubbles, both in size and quantity. A few tiny bubbles don’t count. You’re looking for a reaction similar to the baking soda and vinegar reaction you are probably familiar with.
Optional: check with your hand lens while the reaction is taking place.
Record your observations in your data table.
Wipe your samples dry with a clean, damp cloth.
Test the hardness of your sample with the nail and record it in your data table. If the sample is softer than the nail, you’ll see a scratch and a powder left behind. Scratch it a couple of times to dig up more powder, then add a drop of the vinegar to the powder. Record your results. Did you see bubbles on the powder?

Do not let kids test their minerals with hydrochloric acid. (For teachers demonstrating the HCl version of this test: CaCO₃ + 2HCl → Ca⁺⁺ + 2Cl^—+ H₂O + CO₂) Note: a few rocks, like coquina, oolite, and tufa can produce an extreme reaction with hydrochloric acid because they have a lot of calcite, and/or a lot of pore space that allows for high surface areas (exposing more of the calcium carbonate to the acid). The reaction will be quick, foamy, and vigorous, which is why we only use one drop of acid at a time. Exercises

What state(s) of matter is/are present during the chemical reaction of the acid test?
Write the chemical equation that describes the reaction using your own words. For example, to make water, you’d write: oxygen + hydrogen = water. What would you write for the reaction on the rocks?

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Sedimentary, Metamorphic, and Igneous Rocks

Tuesday September 3, 2013

Clastic rocks come in very different shapes and sizes, but they all have a few characteristics in common. A clast is a grain of sand, gravel, pebble, etc that makes up a rock. Clastic rocks look like they are made up of fragments of other rocks.

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Materials

Small piece of plate glass
Magnifying lens
Vinegar
Paper towel
Shallow dish
Rock samples (in the video: bituminous coal, sandstone, siltstone, shale)

Metamorphic rocks are classified by as being foliated or non-foliated. Foliated rocks have layers, like bands around the rock. Non-foliated rocks don’t have any layers are are solid-looking throughout, although they might have crystals here and there. If the crystals are aligned to form a layer, then it’s a foliated rock.

Igneous rocks are classified as being extrusive or intrusive. An intrusive rock has a courser grain texture without a magnifier. Extrusive rocks need a magnifier to see the finer grains that make up the rock. Some extrusive rocks, like obsidian, need a microscope to see the fine grains.

Download worksheet and exercises

Clastic sedimentary rocks are fragments of other rocks. Geologists look at the tiny particle grains that make up the rock when they name the rock. For example, mudstone is named for its tiny particles of mud and clay, and sandstone is made up of larger grains of sand. The conglomerate rocks look like they are made up of pebbles. Siltstone under a strong magnifier show microscopic grains.

Number and label your samples with your data table.
Take your hand magnifier and look closely at each sample and record the color information on the data table.
Use a dropper to take vinegar out of its bottle.
Drop a few drops onto your sample and watch for a reaction. If you see a reaction, note this in the data table and classify the rock as a chemical rock, not a clastic rock.
Wipe your samples dry with a clean, damp cloth.
Test the hardness of your sample with the nail and record it in your data table using Mohs’ Hardness Scale.

Exercises

Give three types of clastic sedimentary rocks.
How can you tell a clastic from a non-clastic rock?
Does hardness determine a clastic rock? If so, what hardness do you expect a clastic rock to have?

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Burning Coal

Tuesday September 3, 2013

Bituminous coal (also called black coal) is a soft, black organic sedimentary rock that contains 85% carbon. It’s a lower grade than anthracite coal, which contains 93% carbon. Bituminous coal can either be dull or shiny, whereas anthracite is hard and shiny. Lignite, a lower grade than bituminous, is a crumbly, black type of coal that only contains 72% carbon.

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Materials

Votive candle
Paperclip
Hammer (if your piece of coal is large)
Pliers (to bend paperclip)
Lighter with adult help
Cup of water
Rock samples (in the video: bituminous coal, anthracite coal)

Download worksheet and exercises

Coal comes in two main forms: bituminous and anthracite. Bituminous coal is the stuff used to generate energy, whether electricity, heated water, or as a product in other substances. It’s more abundant than anthracite, which is the purer version of coal. Anthracite burns hotter and cleaner, but it’s more scarce. Coal also exists in two other forms as peat, which used to serve as fuel for heating homes as well as lignite, which is more pure than peat but not quite as pure as bituminous.

Coal is one of the two kinds of rocks that are not made from minerals (amber is the other).

Today’s lab lets you burn coal to identify the byproducts of combustion. When coal is burned, it releases volatile compounds that are hazardous to your health, including methane, hydrogen, carbon monoxide, carbon dioxide, nitrogen, and volatile hydrocarbons, but the chemical reaction leaves behind a purer form of carbon than found in the coal itself. So make sure to do this experiment outside!

Move your experiment outside. Do not do this indoors! Fumes generated must be properly ventilated.
Open up and bend the paperclip into a shape that will allow you to hold the coal without it falling off the end. Use pliers to bend the paperclip.
Set a small piece (about the size of a pea) of bituminous coal at the end of the paperclip.
Put on your goggles. NO EXCEPTIONS!
Have an adult light your candle.
Place the coal piece at the top of the flame for the most intense heat.
Look for brown to black smoke to come from the coal. Record your observations in your data table.
When you’re done, place the entire piece of coal in your cup of water.

Optional: If you’ve got a test tube and stand, you can do the following experiment:

Put on your goggles, and pick up the test tube with the test tube holder.
Place a small piece of bituminous coal in the test tube (about the size of a pea).
Place the tube at an angle in a proper holder.
Turn on the heat source, and wave it near the bottom of the test tube for a few minutes, until you notice any slight changes.
As your coal sample heats up, look for bubbles or gas, which is coal gas, one of the first of three things produced by coal. The coal gas was captured and used as fuel in household lamps and streetlights before electricity was available.
As you continue to heat the sample, look for brown stuff along the sides of the tube called coal tar, which is used in dyes, aspirin, textiles, pesticides, and more.
As your sample continues to burn, notice if there are any gray-black solids in the bottom. This will look a lot like ash, but it’s called coke and it’s used to purify metals in a chemical process.

Exercises

What are the three products that coal generates?
Name four types of coal.
What are two things we use coal for?
What type of coal is the most pure?
What is the dominant element in coal?
What are three alternatives to generating energy, instead of using coal?

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Tenacity

Tuesday September 3, 2013

Tenacity is a measure of how resistive a mineral is to breaking, bending, or being crushed. When you exceed that limit, fracture is how the mineral breaks once the tenacity (or tenacious) limit has been exceeded.

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Materials

Hammer (if your piece of coal is large)
Rock samples (in the video: copper, mica, selenite, sulfur)

Download worksheet and exercises

Tenacity is a measure of how a mineral behaves when under stress, like being crushed, bent, torn, or hammered. Minerals will react differently to each type of stress. Minerals can have more than one type of tenacity, since it’s possible for a mineral to have different (or several at the same time) reactions to the stress. Here’s a way to classify their response to stress:

Brittle: The sample crumbles or turns into a powder. Most minerals are brittle, like quartz.
Sectile: These minerals can be separated with a knife, like wax, like gypsum.
Malleable: When you hammer the mineral and it flattens instead of breaks, it’s malleable like silver and copper.
Ductile: A mineral that can be stretched into a wire is called ductile. All true metals are ductile, like copper and gold.
Flexible-Inelastic: When you bend a mineral and release it, it stays in the new shape. It was flexible enough to bend, but it didn’t snap back into its original shape when released, like copper.
Flexible-Elastic: When you bend a mineral and release it, it springs back into its original shape. Minerals that are flexible-elastic are fibrous, like chrysotile serpentine.

Label and number each of your samples with your data table.
Use a hammer and try to break the copper sample. Make sure you do this on a hard surface (like the concrete) so you don’t damage your floor or table!
To test for brittleness, like for sulfur, do a scratch test to see if it leaves a fine powder. Use your streak plate if you think your specimen has a hardness of less than 7.
For sectile tenacity, like with mica, carefully insert a knife into the mineral to see if it goes through. If the knife can penetrate through the sample (be careful with this!), then it’s sectile.
To check for flexibility, like mica and selenite, use only slight pressure so you don’t break your sample. Notice if the sample springs back or retains its new shape when released.
Complete the data table with your observations.

Exercises

What are four different types of tenacity?
How is elastic different from inelastic tenacity?
How many types of tenacity can a mineral have?

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Density

Tuesday September 3, 2013

Density can be found by weighing an object and dividing by the volume of the object, and for geologists, is the same thing as specific gravity. Water has a density of 1, which means that 1 gram of water takes up 1 cubic centimeter of space. Specific gravity is a number you get when you divide the density of an object by the density of water, which happens to be 1 gram/cm3.

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Materials

Measuring cup that has graduation marks for milliliters (mL)
Scale that measures in grams
Rock samples (in the video: quartz, meteorite, pumice)

Download worksheet and exercises

The specific gravity (also called the “s.g.” or “SG”) of a mineral or rock is how we compare the weight of the sample with the weight of an equal volume of water. Low specific gravity substances, like pumice (0.9), are not very dense. High specific gravity substances, like for gold (19.3), are very dense. If the specific gravity is less than 1, it will float on water.

Density is a way to measure two different minerals that might be exactly the same size, but their weights are different. Minerals with a metallic luster tend to be heavier. You’ll find variations for SG within the same minerals due to impurities of the mineral. Along those lines, this test can’t be done for material that is embedded within a rock, only for a single sample.

Here are a few examples for you to compare your samples with:

Amber 1.1
Quartz 1.5
Obsidian 2.5
Amethyst 2.6
Diamond 3.5
Hematite 5.05
Pyrite 5.1
Gold 19.3

Label and number each of your samples and record this on your data table.
Weigh each sample and record the information on your table.
Fill your cup with water and note the level.
Completely submerge your sample and read the new water height.
Subtract #4 from #3 answers to get the amount of water your sample displaces. Record this in your data table.
Find the volume of water displaced for every sample.
Divide the mass of the object by the volume to find the density: ρ = m / V with the units of grams / mL
Note: 1 mL = 1 cm³

Exercises

In your data table, which number was the same for every trial run?
What is the equation for finding density?
How did you find the volume of the rock?

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Luster

Tuesday September 3, 2013

Luster is the way a mineral reflects light, and it depends on the surface reflectivity.

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Materials

Sunlight
Rock samples (in the video: pyrite, fluorite, and serpentine)

Download worksheet and exercises

Every mineral has a particular luster, but some have different luster on different samples. Since it’s gauged by eye and not a scientific instrument, there’s quite a lot to be left to the observer when describing it. Luster is not usually used to identify minerals, since it’s so subjective.

That said, it is useful when describing a sample’s surface, so hold up yours to the light and use the descriptions below to find the one that best describes what you see.

Metallic or splendent luster are found in highly reflective minerals, like gold.
Submetallic luster is found in minerals that have a similar luster to metal, but it’s a bit duller and less reflective. These minerals are opaque and reflect light well. You’ll find submetallic luster in the thin splinter sections of minerals, such as sphalerite, cinnabar, and cuprite.
Vitreous or glassy luster describes 70% of all minerals, and they have the luster of glass. Quartz, calcite, topaz, beryl, tourmaline, and fluorite are examples of glassy luster.
Adamantine lusters (brilliant, like a cut diamond) are for transparent materials that show a very bright shine because they have a high refractive index.
Resinous lusters are usually yellow, orange, or brown minerals that have high refractive indices (like the way sunlight goes through honey).
Silky lusters have very fine fibers aligned in parallel, so it looks like a cloth of silk. Minerals like asbestos, ulexite, and a variety of gypsum called satin spar all have silky luster. If a sample has fibrous luster, it is coarser than a silky luster.
Pearly luster minerals look like the way light reflects off pearls, like the inside an oyster shell. These types of minerals have perfect cleavage, like muscovite and stilbite. Mica also has a pearly luster. Some pearly luster minerals also have an iridescent hue.
Greasy or oily luster looks like fat, and is found in minerals that have a lot of microscopic inclusions, like opal and cordierite. Most greasy luster minerals also feel oily.
Pitchy luster looks a lot like tar, and is found in radioactive minerals.
Waxy luster resembles wax, the way jade and chalcedony look on their surface.
Dull or earthy luster minerals have very little or no luster at all, because they have a surface that scatters the light in all directions, like with Kaolinite. Some geologists say that earthy luster means less luster than dull, but it’s really a close call between the two.

When light strikes a surface, it can be reflected off the surface, like a mirror, or it can pass through, like a window, or both. Metallic luster has most of the light bouncing off the surface, whereas calcite has most passing through the mineral. When light travels through a mineral, it refracts, or changes speed, as it crosses the new material boundary. This is what makes the luster appear different for different materials.

Refraction is how light bends when it travels from one substance to another. When light moves through a prism, it bends, and the amount that it bends is seen as color that comes out the other side. Each color represents a different amount of bending that it went through as it traveled through the prism.

Label and number each of your samples and record this on your data table.
Hold your mineral in the sunlight.
Use the list to find the word that best describes what you see. Look particularly on your sample for a surface that is clean and not tarnished, discolored, or coated. Look at cleaved surfaces and on uneven parts.

Metallic
Submetallic (duller than metallic)
Vitreous or glassy
Adamantine (like a cut diamond)
Resinous (like honey)
Silky (like a silk cloth)

Pearly
Greasy or oily
Pitchy (like tar)
Waxy (like a candle)
Dull or earthy

Record your observations in the data table.

Exercises

What is refraction?
Feldspar has perfect cleavage on two surfaces but fractured on a third. What kind of luster would you say it has?
What type of luster is found on mica?

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Fluorescence

Tuesday September 3, 2013

Fluorescent minerals emit light when exposed to ultraviolet (UV) light, usually in a completely different color than when exposed to white light. UV is invisible to the human eye, and is the wavelength of light that is responsible for sunburns.

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Materials:

Longwave UV light
Sunlight
Rock samples (The four samples at the end of the video are: top left is opalite, top right is calcite, bottom left is norbergite, bottom right is calcite & willemite.)

Download worksheet and exercises

Stars, including our sun, produce all kinds of wavelengths of light, even UV. The UV minerals in this lab contain a substance that reacts with light. It takes the UV light from the sun and then re-emits it in a different wavelength that’s visible to us.

When a particle of UV light hits an atom in the mineral, it collides with an electron which makes the electron jump to a higher, more energetic state that is a bit further from the center of the atom than the electron is used to. That’s how energy gets absorbed by an atom. The amount of energy an electron has determines how far from the atom it has to be.

The electron prefers being in its lower state, so it relaxes and jumps back down, and when it does, it transfers a blip of energy away. This blip of energy is the light we see emitted from the UV mineral. This process continues as long as we see a color coming from the mineral under the UV light.

There are two different types of UV wavelengths: longwave and shortwave. Some minerals fluoresce the same color when exposed to both wavelengths, while others only fluoresce with one type, and still others fluoresce a different color depending on which it’s exposed to. Minerals fluoresce more notably with shortwave UV lamps, but these are more dangerous than longwave since they operate at a wavelength that also kills living tissue.

Shortwave UV lamps and lights should only be operated by an experienced adult. Never use a shortwave light when children are around.

Most minerals do not fluoresce, but in the ones that do, there are either small impurities that fluoresce (called “activators”) or the pure substance itself fluoresces (although this is rare). For a mineral to fluoresce, the impurities present must be in just the right amount. For example, red fluorescent calcite from Franklin, NJ, USA is activated by manganese that’s present, but only if there’s about 3% of it in the mineral. If there’s more than 5% or less than 1% manganese, the sample won’t fluoresce at all. It’s the amount and type of the impurities that determines the color and intensity of the fluorescence.

Fluorescence is not a reliable way to identify a mineral, since some samples will fluoresce with different colors even though they are all the same mineral. Fluorescence is used to determine where the mineral came from, since the colors that the minerals fluoresce usually match the original location of the mineral.

Phosphorescence is when a sample glows even after you turn off the UV light source. This is the type of glow you’ll find in “glow in the dark” toys, where the light slowly fades after you turn off the light. Atoms continue to emit light even after the electrons return to their normal energy states. While it looks like seconds to minutes that the glow lasts, some samples have been found to phosphoresce for years using highly sensitive photographic methods. Only a few minerals phosphoresce, such as calcite from Terlingua, Texas.

Label and number each of your samples and record this on your data table.
Hold your mineral in the sunlight and record the color in the data table.
Go inside and turn off the lights. Hold your sample under a longwave UV light and record the colors that you see.
Complete the data table.

Aragonite
Hackmanite
Calcite
Fluorite
Opalite
Calcite & willemite
Tremolite
Resinous coal
Wernerite

Aragonite
Termolite
Wiollemite
Opalite
Chalcedony
Calcite & willemite
Talc
Resinous coal
Norbergite
Calcite

Exercises

What wavelength is shortwave UV? Longwave UV?
How is fluorescence different from phosphorescence?
Name two minerals that fluoresce in both shortwave and longwave UV light.

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Magnetism

Tuesday September 3, 2013

A magnetic field is the area around a magnet or an electrical current that attracts or repels objects that are placed in the field. The closer the object is to the magnet, the more powerfully it’s going to experience the magnetic effect. Nearly all minerals that are magnetic have iron as a component.

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Materials:

Magnet
Rock samples (samples in the video that stuck to the magnet are lodestone [which is the magnetic form of magnetite] and meteorites)

Download worksheet and exercises

Minerals can become attracted to a magnetic field if they are heated to a certain temperature. These minerals become ferromagnetic after heating them up. Some minerals also act as magnets when they are heated, but this effect is only temporary for as long as the mineral stays at that temperature.

Magnetism is a very useful way of identifying a mineral, because it’s so precise. When testing for magnetism, you’ll get better results if you use the strongest magnet you can find. You’ll find minerals that respond to magnets (without heating them up first) are metallic-looking samples.

Most student-grade geology books refer to minerals that are attracted to magnetic fields as “magnetic,” which leads to confusion because there’s a difference between being “magnetic” (acting as a magnetic field) and being “attracted to magnetic fields.” When you fill out your observations in the data table, keep this in mind when you write down what you see by using the words “magnetic” or “attracted to a magnetic field.”

Label and number each of your samples and record this on your data table.
Hold your mineral close to the magnet and observe how strongly it is attracted to the magnet. How far away do you have to be to start influencing the sample?
Complete the data table.
There are several magnetic properties that geologists use to specify the type of magnetism within a mineral:
- Ferromagnetism is the kind of magnetism you’ll see in magnetite and pyrrhotite, as these have strong attraction to magnetic fields.
- Paramagnetism is a weak attraction to magnetic fields, such as with the minerals hematite and franklinite.
- Diamagnetism occurs in only one mineral, bismuth, which means it’s repelled from magnetic fields.
- Magnetism is found in only one mineral called lodestone, which is the magnetic version of magnetite. It’s really rare, since it’s only found in a couple locations in the entire world. Lodestone is weakly magnetic, but if you drop small paperclips, staples, and iron filings onto a piece, they’ll stick.

Exercises

Is lodestone the same as magnetite?
Which mineral is repelled from any magnetic field?
Which element is usually present in minerals that have magnetic properties?

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Making Limestone

Tuesday September 3, 2013

Out of all the kinds of sedimentary rocks, limestone makes up 10% by volume. People have used limestone in architecture like the Great Pyramids, castles in Europe, and in early 20th century buildings like banks and train stations. Today we use it as white filler in toothpaste, to build roads, make tiles, in cosmetics, and added to breads and cereal as a cheap source of calcium.

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Materials:

Goggles
Distilled white vinegar (you only need a drop, so use a medicine dropper)
Funnel
Straw
2 water bottles
2 paper napkins
Calcium hydroxide (also known as “lime”) This chemical is irritating to skin and eyes, so use your goggles and gloves when handling since it’s a dust. This chemical is toxic and should only be handled by an adult. Find safety information under MSDS Calcium Hydroxide

DO NOT ALLOW CHILDREN TO DO THIS EXPERIMENT. Limewater is TOXIC. This experiment is for demonstration purposes only by an adult.

STUDENTS: You can watch the video and complete the data table and exercises if you’re not able to have an adult do this for you

Download worksheet and exercises

Limestone is a sedimentary rock that is mostly calcium carbonate, and some amazing fossils have been found in limestone. In our experiment today, we are doing a simple chemistry experiment that produces calcium carbonate as the product. The calcium carbonate is created from a chemical reaction of the carbon dioxide from your breath mixed with calcium hydroxide. Only 4-5% of your breath is converted into carbon dioxide, so it takes awhile to get enough carbon dioxide through the solution to form the calcite crystals and see the color change happen.

Put on your goggles and gloves.
Fill one of your water bottles partway with water.
Add a spoonful of calcium hydroxide.
Cap the calcium hydroxide and store safely away.
Place the cap on the water bottle and shake up the solution. Set aside and do not disturb for several minutes.
Fold your napkin into a shape that will fit into your funnel. This is a liner for your funnel that will catch the solids as they are poured into the funnel.
Put a little water into your funnel to dampen the paper napkin liner.
Place the second (empty) water bottle under the funnel.
Pour the limewater solution through the funnel. Don’t pour the sludge at the bottom into the funnel.
Insert a straw into the water bottle with the strained limewater.
Write down the color of the solution. Is it cloudy? Clear?
Blow gently into the straw for several minutes until you see a color change. DO NOT INHALE. Limewater is very toxic!
What color did the color change to? Record your observations in the data table.
Test the calcite by pouring the solution through a new paper funnel.
Place a drop of acetic acid (distilled white vinegar) on the calcite crystals and watch for a slight reaction.

Exercises

What element is present in both calcium carbonate and your breath when you exhale?
Why aren’t kids allowed to do this experiment? What’s the danger?
Where can you find safety information for chemicals?

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Making Sandstone

Tuesday September 3, 2013

Sandstone is a common sedimentary rock that’s composed of quartz crystals cemented together by silica, calcium carbonate, clay or iron oxide. Fossils are often found in sandstone.

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Materials

2 paper cups
Water
Popsicle stick
Sand
Plaster of Paris
Shell (something to make a fossil impression of)
Scissors

Download worksheet and exercises

One way geologists classify sandstone is by the amount of quartz, feldspar, and lithic grains it contains. Quartz sandstone is composed of more than 90% quartz grains, while feldspathic sandstones has less than 90% quartz, but more feldspar than lithic grains. Lithic sandstones have both less than 90% quartz and more lithic grains. In addition, if a geologist calls a sample “clean sandstone,” then it means that there are tiny holes in the sample, like pores. They’ll add the word “arenite” to the name, so you might hear “quartz arenite” which means a sandstone that has more than 90% of its grains as quartz and is also porous.

Pour enough sand to cover the bottom of one of the cups.
In the second cup, make a 1:1 mixture of Plaster of Paris and water. (You can add food dye to make the plaster more visible when layered, but this is optional.)
Stir to combine with the popsicle stick.
Pour a layer right on top of the sand.
Add more sand to the first cup.
Now add more plaster.
Continue adding in layers until you have at least six layers (three of each), but you can do more if you have enough room and materials.
Do not mix the layers.
Cover the last layer with sand.
If you’re making a fossil impression, first rub vegetable oil over it (so the sand doesn’t stick) and press firmly into place without twisting or pushing too hard. Allow it to dry for 24 hours.
When it’s dry, carefully remove the fossil on top and see the impression you’ve made!
Tear away the cup to see the different layers of your homemade sandstone.

Exercises

What elements is calcium carbonate made out of? (Carbon and oxygen.)
How does this experiment look like sandstone? (The tiny grains of sand are glued together by the Plaster of Paris.)
What do you know about a feldspathic arenite sample? (The sample has less than 90% quartz, but more feldspar than lithic grains, and it’s porous.)

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Popcorn Rock

Tuesday September 3, 2013

Popcorn rocks are different than regular dolomite samples because they have a lot more magnesium inside. This was first discovered by a geology professor in the 1980s who was dissolving the limestone around fossils he was studying in his rock samples. When he placed samples of this type in the acid to dissolve, it didn’t dissolve but instead grew new crystals!

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Materials:

“Flowering Rock” dolomite samples
Distilled white vinegar (acetic acid)
Disposable cup or glass jar
Penny
Nail
Streak plate
Water in a graduated container
Scale that measures in grams
Longwave UV light source
Sunlight

Download worksheet and exercises

Dolomite is made of calcium magnesium carbonate (CaMg(CO3)2 and is both a mineral and a rock. Dolomite comes in all kinds of colors, including white, gray, pink, peach, yellow and orange … even colorless. Dolomite gives a white streak, which is hard to see on a white streak plate, and the hardness ranges from 3.4 to 4 on the Moh’s hardness scale. Specific gravity for dolomite is 2.8 to 3, with a vitreous (glassy), pearly luster and rhombohedra cleavage on two planes and conchoidal fracture on the third. It’s brittle (think tenacity), and is usually found around limestone. Dolomite is a chemical rock, since it reacts to acid. Dolomite fluoresces bluish-white when placed under a longwave UV light, and pink when exposed to a shortwave UV light.

You’re first going to classify dolomite and test it for certain properties, and then you’ll grow crystals all over it. If you don’t have a UV light, skip it and perform the rest of the tests.
Complete the first data table for the sample before following the instructions on the video. You are looking for the color, streak, hardness, density, luster, cleavage, fracture, tenacity, acid reaction, and fluorescence.
Don’t wash your dolomite sample. You want the dust layer on top so the crystals start growing more quickly.
Place the sample in your glass jar.
Pour the vinegar into the cup (not directly on your sample) until it’s nearly submerged.
Move your experiment to a warm location.
Observe your rock formation over the next week and record your observations in the second data table. You can opt to take pictures and paste them into the data table.
When all the vinegar has evaporated, remove the sample and put on display (after recording your last observation).

Exercises

What would happen if you warmed the vinegar first, and placed it on a heating pad during your experiment?
What is it in the dolomite samples that make the aragonite crystals grow?
What else can you try instead of vinegar?

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Foam Pumice

Tuesday September 3, 2013

Today we’re making polyurethane foam, which looks a lot like pumice in that it’s lightweight, porous, and cream colored. Polyurethane is a polymer that is used to make a variety of products, including seat cushions, insulation panels, seals and gaskets, roller coaster wheels, escalator rollers, carpet underlay, and wheels for skateboards.
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Materials:

Two disposable plastic cups (must be disposable)
Craft stick
Tart pan
Polyurethane A
Polyurethane B
Sample of pumice for observation

Download worksheet and exercises

Pumice is used to make concrete, cinder blocks, and cement. The Roman Pantheon and aqueducts used pumice as one of their construction materials. Today, you’ll find pumice in polishes because it’s an abrasive. It’s also on the tip of your pencil as an eraser and on your toothbrush inside your toothpaste. If you’ve ever owned a pair of stone-washed jeans, you now know what stone was used to get that look on the pants. Beauty salons use pumice stones for pedicures and chinchillas use powdered pumice to bathe in, since they don’t like to get wet.

Put on your goggles and gloves – NO EXCEPTIONS.
Now, move your entire experiment outside, because this experiment generates fumes that you don’t want to breathe in.
Put the two cups in the pan.
Pour a couple tablespoons of polyurethane A into the first cup.
Pour a couple tablespoons of polyurethane B into the second cup. You need a 1:1 ratio unless otherwise indicated on your package of the product.
Pour one cup into the other, and stir, stir, stir! Your solution will look like honey, so keep stirring. When it starts to get cloudy and foam up, stop stirring.
Touch the bottom of the cup every 10 seconds with a gloved finger (do not touch the liquid itself). What do you notice?
After about a minute, the foam should be rising up and out of the cup. This is polyurethane foam, but don’t touch it yet.
The foam will continue to build up until it spills out over the cup’s lip. DO NOT TOUCH the foam. When the foam is reacting, you should notice heat being released by holding a hand over (without touching!) the top of the rising solution. This reaction is exothermic because it releases heat energy.
When it’s cool, you can touch it with a gloved finger (it’s irritating to the skin, so always use gloves). Record your observations and clean up thoroughly following the instructions for disposal on your package.

Exercises

Name three characteristics of pumice.
How is pumice different from scoria?
What can you use pumice for?

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Test Tube Cannon

Tuesday September 3, 2013

You’ll learn about the key ingredient in an explosive eruption like the one we’re simulating in lab today.

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Materials:

test tube
rubber stopper
toilet paper
goggles
distilled white vinegar
baking soda powder
measuring tape
scale that weighs in grams
ruler

Download worksheet and exercises

Active volcanoes create domes inside the eruption chamber which act like giant plugs, stopping up the magma and building up pressure until … BOOM! The dome explodes and out comes all the material from inside, just like the plug in the test tube.

Baking soda (sodium bicarbonate) and vinegar (acetic acid) chemically react and combine to form carbon dioxide bubbles and a solid form of sodium acetate, which looks like little white flakes at the bottom of the solution.

For baking soda and vinegar, the chemical equation for the reaction looks like this:

NaHCO3 + HC2H3O2 → NaC2H3O2 + H2O + CO2

The chemical reaction actually occurs in two steps. The first reaction looks like this as the vinegar reacts with the baking soda to form sodium acetate and carbonic acid:

NaHCO3 + HC2H3O2 → NaC2H3O2 + H2CO3

But the carbonic acid isn’t a stable molecule, so it breaks down to make the carbon dioxide gas like this:

H2CO3 → H2O + CO2

Since the bubbles are heavier than air, the carbon dioxide builds up and overflows, and stays in the test tube until you dump it out.

Put on your safety goggles. NO EXCEPTIONS!
Tear off a single sheet of toilet paper.
Pour a small pile of baking soda right in the middle of the toilet paper.
Fold the toilet paper in half, and then wrap the sides around until you make a mini-burrito or mini-plug. You want it to fit snugly into your test tube (but don’t put it in there yet!)
Carefully pour vinegar into your test tube. You want about an inch (2-3 cm) of vinegar.
Gently push the toilet paper burrito plug into the test tube, but don’t let it touch the vinegar yet.
Push in your rubber stopper, making sure it’s nice and snug.
Point the stopper away from you or anyone else … like straight up.
Place a thumb on the stopper and shake the tube several times. Remove your thumb before the stopper pops!
After you’ve tried this a few times, it’s time to start taking real measurements. Here’s what you do:
Place the sheet of toilet paper on the scale and zero it (hit “tare”).
Add baking soda and record the mass of the baking soda (in grams) on your data table.
Fill your test tube with vinegar. Rest the bottom of the test tube on the table, and using a ruler, measure many centimeters of vinegar you added and record this number on your data table.
Roll up the toilet paper into the burrito plug and insert it into the test tube.
Add the stopper and shake!
Measure the distance that your stopper traveled in your data sheet and repeat the experiment until you’ve found the perfect ratio of baking soda and vinegar to make the stopper fly the farthest.

Exercises

Does the stopper go further when you add more or less vinegar?
Look at your answer for #1 above. Why is that?
Which gases are produced by this reaction?

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Making Fossils

Tuesday September 3, 2013

Today you get to make your own glop of earth that holds an embedded fossil. If you close the dough over the top of the fossil, you can hammer it apart after it’s had two days to dry.

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Materials:

½ cup dirt
½ cup flour
½ water
½ cup salt
shallow pan
oil
shell or other object to make a fossil impression of

Download worksheet and exercises

There are lots of collecting sites listed in geology field guides and books. Even if sites are popular, new fossils are exposed each spring after the winter’s weather. Another great resource is local fossil clubs, geologic societies, and local museums, especially those that participate in field trips. It’s a lot of fun to go collecting with a group, and many colleges and universities provide unique hands-on opportunities to students interested in earth science classes. Always make sure you’re allowed to collect before you go out with your tools … many local areas require permits.

Mix the dry ingredients together (dirt, flour, and salt) with your hands (or with a spoon).
Add the water and mix together well. Discard any pebbles or gravel from the dirt. You want a gloppy, clay-like mixture that holds together. Add more dry ingredients if needed.
Press the dough ball into the pan, making it ½- to 1-inch thick with ragged edges (fossils aren’t perfect).
Let dry overnight, or at least for a few hours if you’re in a hurry.
Coat the shell or object with oil and press it gently into the dough.
Let it dry thoroughly until it’s hardened. Remove your object and admire!

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Geology Field Trip

Tuesday September 3, 2013

Field trip time! Today you get to sift through sand and excavate your rock samples right on your own desk. This inexpensive set of rock samples contain pieces of not only fossils and gems, but true minerals and rocks also, so take your time and follow the video instructions carefully.

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Materials:

“Geology Field Trip” rock samples: dinosaur bone, horn coral, gastropod, brachiopod, trilobite, oyster, shark’s tooth, petrified wood, crinoid stem, pyrite, magnetite, gypsum, hematite, sulfur, pumice, selenite, limonite, quartz, mica, fluorite, calcite, feldspar, coal, red sandstone, conglomerate, obsidian, scoria, mica schist, quartzite, shale, gneiss, turquenite, rock crystal, agate, and amethyst.
Penny
Nail
Streak plate
Glass plate
Water in a graduated container
Sunlight
Pencil and paper
Handheld magnifier

Download worksheet and exercises

NEW! I’ve improved the worksheet, so you can download the latest edition here.

You’re first going to classify your pile of rocks right along with the instructional step–by-step video. So fire up the video and get your materials out as you complete the data table.
Use the table on the next page to place your rocks once you’ve identified them. Enjoy your second real geologist rock hunt

dinosaur bone
horn coral
gastropod
brachiopod
trilobite
oyster
shark’s tooth
petrified wood
crinoid stem
pyrite
magnetite
gypsum

hematite
sulfur
pumice
selenite
limonite
quartz
mica
fluorite
calcite
feldspar
coal
red sandstone

conglomerate
obsidian
scoria
mica schist
quartzite
shale
gneiss
turquenite
rock crystal
agate
amethyst

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Atmospheres

Sunday September 1, 2013

Scientists do experiments here on Earth to better understand the physics of distant worlds. We’re going
to simulate the different atmospheres and take data based on the model we use.

Each planet has its own unique atmospheric conditions. Mars and Mercury have very thin atmospheres, while Earth has a decent atmosphere (as least, we like to think so). Venus’s atmosphere is so thick and dense (92 times that of the Earth’s) that it heats up the planet so it’s the hottest rock around. Jupiter and Saturn are so gaseous that it’s hard to tell where the atmosphere ends and the planet starts, so scientists define the layers based on the density and temperature changes of the gases. Uranus and Neptune are called ice giants because of the amounts of ice in their atmospheres.

Materials

4 thermometers
3 jars or water bottles
Plastic wrap or clear plastic baggie
Wax paper
Stopwatch

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>
Download Student Worksheet & Exercises

Place one thermometer in direct sunlight. This is like the atmosphere of Mercury and Mars.
Place a second thermometer in a jar and cap it. Place this in sunlight. This is the Earth’s, Jupiter’s and Saturn’s atmosphere.
Line the second jar with wax or tissue paper. Place the third thermometer in the jar and cap it. Place it next to the other two in sunlight. This is the atmosphere on Venus.
Insert the fourth thermometer into a plastic baggie, insert it into the bottle and cap it. Make sure the baggie is loose. This is Neptune and Uranus.
Record your data observations in the table, taking data every couple of minutes.

What’s Going On?

Venus is hot enough to melt cannonballs and crush any spaceship that tries to land on the surface. Carbon dioxide is a “greenhouse gas,” meaning that some wavelengths of light can pass through it, but specifically not infrared light, which is also known as heat. Light from the Sun either bounces off the upper cloud layers and back into space, or penetrates the clouds and strikes the surface of Venus, warming up the land. The ground radiates the heat back out, but the carbon dioxide atmosphere is so dense and thick that it traps and keeps the heat down on the surface of the planet. Think of rolling up your windows in your car on a hot day.

The heat is so intense on Venus that the carbon normally locked into rocks sublimated (turned straight from solid to gas) and added to the carbon in the atmosphere, to make even more carbon dioxide.

Mercury doesn’t have much of an atmosphere, which is just like a bare thermometer. There’s nothing to hold onto the heat that strikes the surface. Mars is in a similar situation.

Earth’s atmosphere is simulated by placing the thermometer in a bottle. The Earth has a cloud layer that keeps some of the heat on the planet, but most of it does get radiated back into space. When the clouds are in at night, the planet stays warmer than when it’s clear (and cold).

Venus’s heavy, dense carbon dioxide atmosphere is simulated by using the waxed paper. Venus is the hottest planet in our solar system because of the runaway greenhouse effect that traps most of the heat that makes it through the atmosphere, bouncing it back down to the surface. The average temperature of Venus is over 900^oF.

Jupiter and Saturn’s atmospheres are thinner layers of hydrogen and helium than deeper in the core.

Uranus and Neptune are called ice giants because of the amounts of ice in their atmospheres. Their atmospheres are also made of mostly hydrogen and helium.

Exercises

Which atmosphere reached the highest temperature?
Each of the jars received the same amount of energy from the Sun. Why is this not quite like the real solar system?

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Exercises for Geology

Sunday September 1, 2013

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What is the definition of a rock?
What does it mean if there’s no streak left on the streak plate?
Give an example of a kind of rock that leaves a streak a different color than its surface color.
If a mineral scratches a penny but doesn’t get scratched by a nail, can you approximate its hardness?
Give examples of the hardest and softest minerals on the Mohs’ Scale of Hardness.
Name three properties geologists look for when they try to categorize a mineral.
If you break a sample of quartz and find that it has no clean surfaces of separation, what kind of cleavage does it show?
What are two things we use coal for?
What is the equation for finding density?
10. How is fluorescence different from phosphorescence?
Is lodestone the same as magnetite?
Name three characteristics of pumice.
What is a crystal, and how is it different from a mineral and a rock?

Need answers?
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Exercises for Atmosphere

Sunday September 1, 2013

Let’s see how much you’ve picked up with these experiments and the reading – answer as best as you can. (No peeking at the answers until you’re done!) Just relax and see what jumps to mind when you read the question. You can also print these out and jot down your answers in your science notebook.
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1. How does radiation travel?
a. As a beam
b. As a wave
c. as a molecule

2. Where does most of the energy on earth come from?
a. Underground
b. The Sun
c. The Oceans

3. What is one way that we use energy from the sun?

4. Which instrument measures humidity?
a. Thermometer
b. Barometer
c. Hygrometer
d. Rain Gauge

5. What is the unit of measurement for temperature here in the USA?
a. Newtons
b. Joules
c. Fahrenheit
d. Celsius

6. What is another unit of measurement used for temperature?
a. Fahrenheit
b. Celsius
c. Joules
d. Newtons

7. What is the science called that investigates the weather and patterns of the Earth’s atmosphere?
a. Zoology
b. Biology
c. Meteorology
d. Nephology

8. What are clouds made of?
a. Nitrogen
b. Water
c. Oxygen
d. Iridium

9. What form of water exists in clouds
a. Water vapor
b. Liquid water
c. Frozen water

10. What is the name of someone who studies the weather?
a. Oncologist
b. Herpetologist
c. Climatologist
d. Meteorologist
e. Asteroidologist

11. What is the type of energy that comes from the sun?
a. Potential
b. Kinetic
c. Electronic
d. Radiation

12. What principle describes how pressure behaves in a moving fluid?
a. Avogadro’s Principle
b. Bernoulli’s Principle
c. Boyle’s Law
d. Pascal’s Wager

13. A higher pressure will ________ an object.

14. An object experiences pressure in the Earth’s atmosphere in which direction more?
a. Upwards
b. Downwards
c. Equally in all directions

15. If an object is higher in altitude above the earth, it experiences which pressure in relationship to an object at sea level?
a. Greater Pressure
b. Less Pressure
c. Equal Pressure

Need answers?
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Answers to Exercises

Sunday September 1, 2013

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!

Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here.
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Answers:

How does radiation travel? (as a wave)
Where does most of the energy on earth come from? (the Sun)
What is one way that we use energy from the sun? (appropriate energy answer)
Which instrument measures humidity? (Hygrometer)
What is the unit of measurement for temperature here in the USA? (Fahrenheit)
What is another unit of measurement used for temperature? (Celsius)
What is the science called that investigates the weather and patterns of the Earth’s atmosphere? (Meteorology)
What are clouds made of? (Water)
What form of water exists in clouds (Water vapor)
What is the name of someone who studies the weather? (Meteorologist)
What is the type of energy that comes from the sun? (Radiation)
What principle describes how pressure behaves in a moving fluid? (Bernoulli’s principle)
A higher pressure will ________ an object. (Push on)
An object experiences pressure in the Earth’s atmosphere in which direction more? (Equally in all directions)
If an object is higher in altitude above the earth, it experiences which pressure in relationship to an object at sea level? (Less pressure)

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Answers to Exercises

Sunday September 1, 2013

What is the definition of a rock? (Something that is made of two or more minerals.)
What does it mean if there’s no streak left on the streak plate? (The mineral is harder than the streak plate, which means it has a hardness of above 7.)
Give an example of a kind of rock that leaves a streak a different color than its surface color. (Pyrite is gold, but its streak is green-black.)
If a mineral scratches a penny but doesn’t get scratched by a nail, can you approximate its hardness? (Over 5.5)
Give examples of the hardest and softest minerals on the Mohs’ Scale. (Diamond = 10, Talc = 1)
Name three properties geologists look for when they try to categorize a mineral. (Color, hardness, fluorescence, magnetism, luster, how they break, if they react to acid, etc.)
If you break a sample of quartz and find that it has no clean surfaces of separation, what kind of cleavage does it show? (none)
What are two things we use coal for? (heating water and generating electricity)
What is the equation for finding density? (density = m/V)
How is fluorescence different from phosphorescence? (Minerals that are fluorescent glow when exposed to a UV light. Minerals that continue to emit light even after the UV light has been switched off are phosphorescent.)
Is lodestone the same as magnetite? (Lodestone is the magnetic version of magnetite.)
Name three characteristics of pumice. (light-colored, floats on water, and is porous.)
What is a crystal, and how is it different from a mineral and a rock? (Crystals are a structure of a regular pattern of atoms within a solid. A mineral is an inorganic substance. All minerals are crystalline. Rocks are composed of two or more minerals. Not all crystals are minerals.)

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Giant Crystals

Saturday August 31, 2013

The Cave of Crystals in Mexico has the world’s largest selenite (gypsum) crystals about 1,000 feet below the surface in a hot cavern. Some of the crystals are over 50 tons in weight and 35 feet in length!
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Scientists that study these crystals have to wear special suits filled with ice packs along with respirators so they can stay cool and comfortable, since the air is thick with water 99% humidity and temperatures from 110-136 degrees Fahrenheit. Without these special suits, people would last only ten minutes, which means that most of the cave is still largely unexplored.

If you’re interested in these caves, look up information on the Naica Project to learn more.

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Rock Hound Workshop

Saturday August 31, 2013

Today you get to sort and identify as many rocks as you can as you test for streak, hardness, fluorescence, color, magnetism, chemical reactions, and more with this unique set of rocks. You may have to do a little research on the ones that are not yet familiar to you!

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Materials:

“Washington Student Rock Pack” (see list below for samples that are included)
Penny
Nail
Streak plate
Water in a graduated container
Scale that measures in grams
Longwave UV light source

Download worksheet and exercises

NEW! I’ve improved the worksheet, so you can download the latest edition here.

You’re first going to classify your pile of rocks right along with the instructional step–by-step video. So fire up the video and get your materials out as you complete the data table.
You’ll be testing for color, streak, hardness, density, luster, cleavage, fracture, tenacity, acid reaction, and fluorescence. Enjoy your third real geologist rock hunt!
Here are the minerals and rocks included with this set:

Calcite
Calcareous Tufa
Pyroxene
Limestone
Gypsum
Conglomerate
Amphibole
Fossiliferous Limestone
Quartz
Sandstone
Mica – Muscovite
Shale
Feldspar – Microcline
Bituminous Coal
Feldspar – Plagioclase

Clay
Bauxite – Aluminum Ore
Porphyry
Limonite – Iron Ore
Obsidian (or Pitchstone)
Hematite – Iron Ore
Felsite
Pyrolusite – Manganese Ore
Pumice
Magnetite – Iron Ore
Basalt
Copper Ore

Gabbro
Pyrite – Iron-Sulfur Ore
Granite
Fluorite
Slate
Sulfur
Gneiss
Barite
Marble
Graphite
Mica Schist
Talc
Quartzite

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Earthquakes!

Saturday January 28, 2012

When two blocks of the Earth slip past each other suddenly, that’s what we call an earthquake! From a physics point of view, earthquakes are a release of the elastic potential energy that builds up. Most energy is released as heat, not as shaking, during an earthquake. 90% of all earthquakes happen along the Ring of Fire, which is the active zone that surrounds the Pacific Ocean.

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The Earth has four main layers: the hard skin on the surface is the crust which extends only 30 miles; the hot magma section is a soupy mass of rock that extends approximately 1800 miles; and the core which is made out of two parts: the hot liquid metal outer core surrounds the solid nickel -iron inner core.

The plates on the crust float on magma, which is a lot like the consistency tar. The crust has seven main tectonic plates that slide around and can either slide apart from each other (called a normal fault that is usually found on the sea floor), collide into each other (called a thrust fault), or move in opposite directions (strike-slip fault) at different speeds. Where the plates are sliding apart on the sea floor, the temperature of the water can rise over 1200^oF. Scientists measure the speeds of the plates moving from 1 to 10 inches per year.

There are three different waves that travel through the planet when an earthquake happens. The first waves are the compression-type “P-waves” (primary waves), which travel through the entire planet, including liquid water and solid rock. Most people don’t notice the P-waves, but they do notice the secondary “S-waves”, which follow 60-90 seconds after the P-waves. Following the S-waves are the surface waves, which are like when you wave a bed sheet up and down.

Earthquakes are detected and measured by many different types of instruments, like strain gauges, creep meters, tilt sensors, seismometers, x-ray imagery, and more. These detectors aren’t perfect, though. Earthquake detectors not only discover earthquakes but also glacier movement, nuclear explosions, meteor impacts, and volcano eruptions!

After you watch the video, click the link to do your seismology calculations to figure out both the epicenter and the magnitude of four different earthquakes:

Japan Earthquake 1995 (map answer)
Los Prieta California Earthquake 1989 (map answer)
Mexico Earthquake 1978 (map answer)
Northridge California Earthquake 1994 (map answer)

If you’d like to measure the Earth’s Magnetic Pulse, you can do that here.

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How Much Energy Does the Sun Produce?

Friday November 4, 2011

Without the sun, there would be no life on Earth. The sun warms the earth, generates wind, and carries water into the air to produce rain and snow. The energy of the sun provides sunlight for all the plant life on our planet, and through plants provides energy for all animals.

The sun is like a giant furnace in which hydrogen nuclei (atoms without electrons) are constantly smashed together to form helium nuclei. This process is called nuclear fusion. In this process, 3.6 billion kilograms (8 billion pounds) of matter are converted to pure energy every second. The temperature in the sun exceeds 15 million degrees.

Nuclear fusion is one kind of energy. Other forms of energy include: mechanical energy, heat, electrical energy, chemical energy, and light. Mechanical energy is the energy of organized motion, such as a turning wheel. Heat is the energy of random motion, such as a cup of hot water. Electrical energy is the energy of moving charged particles or electrons, such as a current in a wire. Chemical energy is the energy stored in bonds that hold atoms together. Light is any form of electromagnetic waves, such as X rays, microwaves, radio waves, ultraviolet light, or visible light.

Energy can be converted from one from to another. For example, the nuclear energy of the sun is converted to light, which goes through space to the earth. Solar collectors of mirrors can be used to focus some of that light to heat water to steam. This steam can be used to turn a turbine, which can power a generator to produce electricity.

Most of our energy needs are met by burning fossil fuels such as coal, oil, gasoline, and natural gas. The chemical energy stored in these substances is released by burning these fuels. When fossil fuels burn, they combine with oxygen in the air and produce heat and light.

Fossil fuels are not renewable. When they are used up, they are gone forever. However, renewable energy sources such as wind, sun, geothermal, biomass and water power are renewable. They can be used over and over to generate the energy to run our society.

Tremendous amounts of renewable energy are available. For example, the solar energy that falls on just the road surfaces in the United States is equal to the entire energy needs of the country. Although there are sufficient amounts of renewable energy, we must improve our methods of collecting, concentrating, and converting renewable energy into useful forms.

In the following experiments, you will learn something about the amount of energy the sun produces at the earth’s surface and how heat energy can be stored.
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Materials

Water
Disposable, aluminum pie pan
Paint brush
Measuring cups
Watch or clock
Newspaper
Black paint or spray paint (flat, not shiny)

Procedure

Go outside and spread out a sheet of newspaper. Place an aluminum pie pan on the newspaper. Carefully bend one spot on the edge of the pie pan to make a spout shape. This will allow you to more easily pour water out of the pan. Have an adult help you paint the inside of the aluminum pie pan. You can use a brush and a can of paint or spray paint. Be sure not to get the paint on anything except the disposable pie pan and the newspaper. After painting, set the pie pan where the paint can dry overnight.

You will need to do the rest of this experiment on a warm, sunny day. You do not want the pie pan to be in the shade. Set the aluminum pie pan in a warm, sunny spot. The sun will need to constantly shine on the pie pan. The black color of the pie pan allows it to absorb, rather than reflect, solar energy. You will need to begin the experiment about

11:00 A.M., so the solar heating will be done when the sun is high in the sky.

Add exactly one cup of water to the pie pan. Wait four hours while the sun is shining on the pan of water. After exactly four hours of sunshine, carefully pour the remaining water from the pie pan into a one-half or one-fourth measuring cup. Use these measuring cups to estimate the amount of remaining water to the nearest one-eighth of a cup.

Observations

Is the amount of water in the pie pan less than when you began the experiment? How much water is left in the pie pan after four hours of sunlight?

Discussion

You will probably observe that the amount of water in the pie pan is less after four hours of sunlight exposure. Where did the water go? As the sunlight shines on the dark surface of the painted pie pan, solar energy is absorbed and heats the pan and the water. This energy causes a portion of the water to evaporate. As water evaporates, it leaves the liquid form and goes into the air as a gas (water vapor). You will probably find that some, but not all, of the water evaporated.

Scientists use the unit of joule as a measure of energy. However, you may find it helpful to think in units of dietary calories instead of joules. One dietary calorie is equal to 4,184 joules of energy. One cup of breakfast cereal with one-half cup of milk would have about 240 dietary calories, or approximately 1,000,000 joules of energy. Although the earth receives only a tiny portion of the total energy output of the sun, the earth has a constant supply of 173 million billion (173,000,000,000,000,000) watts of solar power. A watt is a unit of power equal to a joule of energy used per second. For comparison, a typical light bulb to run a lamp in your home might require 100 watts of power. A million watts could supply the energy needs of about 500 average American homes.

Use the table below to determine the solar energy required to evaporate a certain amount of water. The amount of water remaining in the pan will allow you to determine how much energy was used, how much power was used, and the amount of power per area.

Your results will probably be in the middle range of this table. For example, if one-half of your water evaporated, then the water remaining would be one-half cup. Thus, the energy used to evaporate this water would be 289,000 joules of energy. This energy would give a power of 20 watts, and a power per area of 800 watts per square meter (watts / meter²).

Solar Energy Required to Evaporate Water
Water Remaining (cup)	Water Evaporated (cup)	Energy Used (joules)	Power Used (watts)	Power per Area (watts / meter²⁾
1	0	0	0	0
7/8	1/8	72,250	5	200
3/4	1/4	144,500	10	400
5/8	3/8	216,750	15	600
1/2	1/2	289,000	20	800
3/8	5/8	361,250	25	1000
1/4	3/4	433,500	30	1200
1/8	7/8	505,750	35	1400
0	1	578,000	40	1600

The following procedure was used to generate the numbers in the Table. It is known that it takes 578,000 joules of energy to evaporate one cup of water. This known energy per cup is multiplied by the fraction of a cup that was evaporated. This gives the solar energy used to evaporate the water in the pie pan. The energy is divided by the number of seconds in four hours (14,400 seconds). This gives the power of the solar energy striking the pie pan, since a watt is equal to a joule per second. Finally, the power (in watts) is divided by the surface area of the pie pan (0.025 square meters) to give the power per area.

When the sun is overhead, the intensity of solar energy can be as much as 1,000 watts per square meter. If all of this energy could be converted to electricity, one square meter of sunshine would be enough to run ten 100-watt light bulbs. However, our current solar cells that convert sunlight to electricity are able to change only about 15 percent of the light to electricity.

You can see from this experiment that there is tremendous energy available from our sun. Most of this energy warms our planet or is reflected back into space. Among other things, the remaining portion of energy powers our water cycle, producing rain and snow, or provides plants with the energy they need to live.

Scientists and engineers are learning more about trapping solar energy and converting it to useful power. It has been estimated that all forms of potentially available renewable energy (wind, water, biomass, and direct solar) have an energy equivalent to 80 trillion barrels of oil. In other words, one year of renewable solar energy is 5,000 times greater than the current yearly energy needs of the United States. In comparison, it has been estimated that all the remaining coal, oil, natural gas, and other potential nonrenewable energy reserves of the United States are equal to about 8 trillion barrels of oil.

Since we do not yet know how to use a significant portion of this renewable energy, much work remains to be done. In the remainder of this book you will learn more about our current ability to use renewable energy and the promise it may hold for the future.

Other Things to Try

Repeat this experiment using different amounts of water on different days and compare the solar power you find.

Repeat this experiment in the late afternoon, when the sun is lower in the sky. How do your result compare to this experiment?
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How Can Water Be Used to Store Heat Energy?

Friday November 4, 2011

Temperature is a measure of the average hotness of an object. The hotter an object, the higher its temperature. As the temperature is raised, the atoms and molecules in an object move faster. The molecules in hot water move faster than the molecules in cold water. Remember that the heat energy stored in an object depends on both the temperature and the amount of the substance. A smaller amount of water will have less heat energy than a larger amount of water at the same temperature.

Increasing the temperature of a large body of water is one way to store heat energy for later use. A large container filled with salt water, called brine, may be used to absorb heat energy during the day when it is warm. This energy will be held in the salt water until the night when it is cooler. This stored heat energy can be released at night to warm a house or building. This is one way to store the sun’s heat energy until it is needed.

Solar ponds are used to store energy from the sun. Temperatures close to 100°C (212°F) have been achieved in solar ponds. Solar ponds contain a layer of fresh water above a layer of salt water. Because the salt water is heavier, it remains at the bottom of the pond-even as it gets quite hot. A black plastic bottom helps absorb solar energy from sunlight. The water on top serves to insulate and trap the heat in the pond.

In a fresh water pond, as the water on the bottom is heated from sunlight, the hot water becomes lighter and rises to the top of the pond. This convection or movement of hot water to the top tends to carry away excess heat. However, in a salt water pond, there is no convection so heat is trapped. In Israel a series of salt water, solar ponds were developed around the Dead Sea. The heat stored in these solar ponds has been used to run turbines and generate electricity.
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Materials

Two paper cups
Measuring cups
Hot water
Watch or clock
Sink
Refrigerator (with freezer compartment)

Download Student Worksheet & Exercises

Procedure

Turn on the hot water faucet of a sink and wait several minutes until the water is hot. Be careful not to burn yourself with this hot water. Add one-fourth cup of this hot water to the first paper cup. Add one cup of hot water to the second paper cup. Place both of these cups in the freezer compartment of a refrigerator.

After thirty minutes check the water in each cup. Return the cups to the freezer compartment and check them again after fifteen minutes. Keep checking the cups each fifteen minutes until the water in one of the cups is frozen.

Observations

Does the water in the cups freeze at the same time? Does the water in one of the cups freeze first? How long does it take for the water to freeze?

Discussion

You will probably observe that the smaller amount of water in the first cup freezes prior to the larger amount of water in the second cup. Both cups were filled with the same hot water. However, even though the water in both cups was at the same temperature, they did not freeze at the same time. The amount of heat energy stored by the water depends on both the temperature and the amount of water.

We expect that the more heat energy stored in the cup, the longer it takes the water in the cup to freeze. Since one cup of water has more heat energy than one-fourth cup of water, it takes the larger amount of water longer to freeze.

Other Things to Try

Place one-half cup of hot tap water in one cup. Place one-half cup of cool tap water in a second cup. Put both cups in the freezer compartment of a refrigerator and check them every fifteen minutes until the water freezes solid. Which cup of water do you think has more heat energy? Which cup of water do you think will freeze first?

Place one cup of water in one paper cup and one-fourth cup of water in a second paper cup. Put both cups in the freezer of a refrigerator and leave overnight. The next day remove both cups of frozen water. Set the two cups out in the room. Observe the time it takes each piece of ice to melt. Which piece of ice do you think will melt first? Which piece will require more heat energy to cause it to melt?

Exercises

What type of heat transfer is at work in a solar pond?
1. Kinetic
2. Conduction
3. Potential
4. Convection
5. Radiation
What units do we use to measure energy?
1. Kilowatts
2. Joules
3. Newtons
4. Kilowatt-hours
Draw a diagram of a solar pond in the space below:

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Can Wind Be Used as a Source of Energy?

Friday November 4, 2011

The United States has large reserves of coal, natural gas, and crude oil which is used to make gasoline. However, the United States uses the energy of millions of barrels of crude oil every day, and it must import about half its crude oil from other countries.

Burning fossil fuels (oil, coal, gasoline, and natural gas) produces carbon dioxide gas. Carbon dioxide is one of the main greenhouse gases that may contribute to global warming. In addition, burning coal and gasoline can produce pollution molecules that contribute to smog and acid rain.

Using renewable energy-such as solar, wind, water, biomass, and geothermal-could help reduce pollution, prevent global warming, and decrease acid rain. Nuclear energy also has these advantages, but it requires storing radioactive wastes generated by nuclear power plants. Currently, renewable energy produces only a small part of the energy needs of the

United States. However, as technology improves, renewable energy should become less expensive and more common.

Hydropower (water power) is the least expensive way to produce I electricity. The sun causes water to evaporate. The evaporated water falls to the earth as rain or snow and fills lakes. Hydropower uses water stored in lakes behind dams. As water flows through a dam, the falling water turns turbines that run generators to produce electricity.

Currently, geothermal energy (heat inside the earth), biomass (energy from plants), solar energy (light from concentrated sunlight), and wind are being used to generate electricity. For example, in California there are more than sixteen thousand (16,000) wind turbines that generate enough power to supply a city the size of San Francisco with electricity.

In addition to producing more energy, we can also help meet our energy needs through conservation. Conservation means using less energy and using it more efficiently.

In the following experiments, you will use wind to do work, examine how batteries can store energy, and see how insulation can save energy.
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Materials

Pinwheel (can be purchased or madefrom construction paper)
Paper clips
Tape
Small shoe box (children’s size)
Electric fan
Lightweight string (about 4 feet long)
Plastic straw (longer than the width of the shoe box)
Hole punch

Download Student Worksheet & Exercises

Procedure

In this activity, you will try to use the energy in the wind to lift a set of six paper clips. You will first need to construct your windmill.

Use a hole punch to punch holes in the opposite sides across the width of a small, cardboard shoe box. Use the narrow sides of the box so the two holes are less than six inches (15 centimeters) apart. Make sure the holes are directly opposite each other. Place a plastic straw through the two holes. You may need to use the hole punch to enlarge the holes so the straw can rotate within the holes. The ends of the straw should extend out either side of the box.

Use the blades from a purchased pinwheel, or cut and fold a square piece of construction paper into the shape of a pinwheel. Next you will need to attach the pinwheel blades to one end of the straw. Partially unfold a small paper clip and insert the larger end into the straw. Push the straightened end of the paper clip through the center of the pinwheel. Bend this end of the paper clip and tape it to the outside of the pinwheel.

Set the electric fan on a table or countertop. Hold the shoe box so that the pinwheel is free to turn. HAVE AN ADULT PLUG IN AND TURN ON THE FAN. Move the windmill box to direct the breeze from the fan toward the blades of the pinwheel. Move the box until you find the best angle of the fan to the pinwheel so that the pinwheel turns freely and rapidly.

Turn off the fan. Now tape one end of the string to the side of the straw with no pinwheel just outside the box, and wrap the string around the straw a few times. Tie the other end of the string to a paper clip. Attach five other paper clips to the paper clip tied to the string. Allow the string to hang down so that the paper clips on the end of the string rest on the floor.

Now, you will test to see if your windmill can convert wind power to do work and lift the paper clips off the ground. Turn on the fan and hold the box where you did before to make the pinwheel turn.

Observations

Does the windmill turn the straw? Does the string wrap around the straw as the straw turns? What happens to the paper clips?

Discussion

You should observe the straw shaft turning as the wind from the fan is directed toward the blades of the pinwheel. As the pinwheel turns, it should wrap the string around the straw and lift the paper clips into the air. Your windmill converts the energy of the wind to work and lifts the weight of the paper clips. If your windmill is not working, then examine all the parts.

Compare your setup to the drawing, and see if any changes need to be made in your construction.

One way to store the energy produced by a windmill is to lift a weight. When the weight is allowed to fall, work can be produced. Weights in a grandfather clock are used to store energy and can run a clock for a week or longer. A windmill’s energy can be used to pump water to a storage area at a higher elevation. Later, this water can be allowed to fall through a turbine which turns a generator and produces electricity.

Electricity can also be produced directly from wind power. The shaft, or rod to which the windmill blades are attached, can be used to turn a generator. A generator or dynamo is used to convert mechanical energy into electrical energy. Power conversion units can change the direct current that wind generates to an alternating current. The alternating current can be fed directly into utility lines and used in our homes.

The sun is the original source of wind power. Without the sun to heat the earth, there would be no wind. The energy of the sun heats the earth, but all parts of the earth are not at the same temperature. These differences in temperature are responsible for global and local patterns of wind. For example, during the day a constant wind blows from the sea toward the land along coastal regions. Air above the hotter land rises and cooler, heavier air above the ocean moves in to take its place.

The power of the wind can be harnessed to do work. For at least 4,000 years, the wind has been used to move sailing ships. The wind has enough power to move ships across oceans and around the world.

For at least 1,000 years, windmills have been used for pumping water and turning

stones to grind grain. Millions of windmills have been used on the plains of America, Africa, and Australia to pump water from deep wells for livestock and humans.

In this century, windmills or wind engines have been used to generate electricity. Over 15,000 wind engines were installed in California in the 1980s. These wind engines have the capability to produce up to 1.5 billion watts of electricity. In California in 1987, wind was used to produce as much electricity as the city of San Francisco uses in an entire year.

Other Things to Try

Repeat this experiment and find the maximum weight you can lift with your windmill. Try more paper clips or try a heavier weight such as a pen.

List some of the problems associated with using windmills. What happens when the wind is blowing too gently? What happens if the wind blows strongly, such as in a storm? Do you think the area where you live is windy enough for wind engines to produce electricity?

Exercises

Name three sources of renewable energy:
What does the sun have to do with wind?
Name three examples of wind power in historical or current usage:

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Cartesian Diver

Sunday October 23, 2011

Rene Descartes (1596-1650) was a French scientist and mathematician who used this same experiment show people about buoyancy. By squeezing the bottle, the test tube (diver) sinks and when released, the test tube surfaces. You can add hooks, rocks, and more to your set up to make this into a buoyancy game!
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The test tube sinks because the when you squeeze the bottle, you increase the pressure of the water and this forces water up into the test tube, which then compresses the air inside the tube. When this happens, it adds enough mass to cause it to sink. Releasing the squeeze on the bottle means that you decrease the pressure and the water is forced back out of the tube.

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Special Science Teleclass: Renewable & Alternative Energy

Sunday October 2, 2011

This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn!

Discover the world of clean, renewable energy that scientists are developing today! Explore how they are harnessing the energy of tides and waves, lean how cars can run on just sunlight and water, tour a hydroelectric power plant, visit the largest wind farms on the planet, and more! You’ll learn how streets are being designed to generate electricity, how teenagers are making jet fuel from pond scum in their garage, and how 70 million tons of salt can provide free, clean energy 24 hours a day forever! During class, you’ll learn how to bake solar cookies, magni-fry marshmallows and do the experiment with light Einstein won a Nobel prize for that is the basis of all photovoltaic energy today.

Materials:

One cup each: hot (not boiling), cold, and room temperature water
Cardboard box, shoebox size or larger.
Aluminum foil
Plastic wrap (like Saran wrap or Cling wrap)
Hot glue, razor, scissors, tape
Wooden skewers (BBQ-style)
Black construction paper
Cookie dough (your favorite kind!)
Chocolate, large marshmallows, & graham crackers if you want to make s’mores! If not, try just the large marshmallow.
Large page magnifier (also called a Fresnel lens, found at drug stores or places that also sell reading glasses, or at Amazon.com)

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What’s Going On?

For the main experiment:

The Fresnel (“FRAY-nell”) lens is a lot like a magnifying glass. Convex lenses (like a handheld magnifier) are thicker in the middle – you can actually feel it with your fingers. A Fresnel lens was first used in the 1800s to focus the beam in a lighthouse. It has lots of ridges you can feel with your fingers. It’s basically a series of magnifying lenses stacked together in rings (like in a tree trunk) to magnify an image.

The Fresnel lens in this project is focusing the incoming sunlight much more powerfully than a regular hand held magnifier. But focusing the light is only part of the story with your roaster. The other part is how your food cooks as the light hits it. If your food is light-colored, it’s going to cook slower than darker (or charred) food. Notice how the burnt spots on your food heat up more quickly!

The best thing about Fresnel lenses is that they are lightweight, so they can be very large (which is why light houses used these designs). Fresnel lenses curve to keep the focus at the same point, no matter close your light source is.

Questions to Ask

What other kinds of food can you roast with your setup?
Does a white marshmallow or chocolate-covered marshmallow cook faster? Why?
Does it matter what angle you point your roaster at?
Will it work with an indoor light?
Why do you need the foil? Can you skip it?
Do we have to use a Fresnel lens? What about a handheld magnifier – would that work?

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Instant Ice

Thursday June 30, 2011

Supercooling a liquid is a really neat way of keeping the liquid a liquid below the freezing temperature. Normally, when you decrease the temperature of water below 32^oF, it turns into ice. But if you do it gently and slowly enough, it will stay a liquid, albeit a really cold one!

In nature, you’ll find supercooled water drops in freezing rain and also inside cumulus clouds. Pilots that fly through these clouds need to pay careful attention, as ice can instantly form on the instrument ports causing the instruments to fail. More dangerous is when it forms on the wings, changing the shape of the wing and causing the wing to stop producing lift. Most planes have de-icing capabilities, but the pilot still needs to turn it on.

We’re going to supercool water, and then disturb it to watch the crystals grow right before our eyes! While we’re only going to supercool it a couple of degrees, scientists can actually supercool water to below -43^oF!

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Materials:

water
glass
bowl
ice
salt

Download Student Worksheet & Exercises

Don’t mix up the idea of supercooling with “freezing point depression”. Supercooling is when you keep the solution a liquid below the freezing temperature (where it normally turns into a solid) without adding anything to the solution. “Freezing point depression” is when you lay salt on the roads to melt the snow – you are lowering the freezing point by adding something, so the solution has a lower freezing point than the pure solvent.

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Hot Ice Sculptures

Thursday June 30, 2011

Did you know that supercooled liquids need to heat up in order to freeze into a solid? It’s totally backwards, I know…but it’s true! Here’s the deal:

A supercooled liquid is a liquid that you slowly and carefully bring down the temperature below the normal freezing point and still have it be a liquid. We did this in our Instant Ice experiment.

Since the temperature is now below the freezing point, if you disturb the solution, it will need to heat up in order to go back up to the freezing point in order to turn into a solid.

When this happens, the solution gives off heat as it freezes. So instead of cold ice, you have hot ice. Weird, isn’t it?

Sodium acetate is a colorless salt used making rubber, dying clothing, and neutralizing sulfuric acid (the acid found in car batteries) spills. It’s also commonly available in heating packs, since the liquid-solid process is completely reversible – you can melt the solid back into a liquid and do this experiment over and over again!

The crystals melt at 136^oF (58^oC), so you can pop this in a saucepan of boiling water (wrap it in a towel first so you don’t melt the bag) for about 10 minutes to liquify the crystals.

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Materials:

Sodium Acetate
Disposable aluminum pie plate

Download Student Worksheet & Exercises

You have seen this stuff before – when you combined baking soda and vinegar in a cup, the white stuff at the bottom of the cup left over from the reaction is sodium acetate. (No white stuff? Then it’s mixed in solution with the water. If you heat the solution and boil off all the water, you’ll find white crystals in the bottom of your pan.) The bubbles released from the baking soda-vinegar reaction are carbon dioxide.

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Cloud Tracker Weather Instrument

Wednesday June 29, 2011

One of the most remarkable images of our planet has always been how dynamic the atmosphere is a photo of the Earth taken from space usually shows swirling masses of white wispy clouds, circling and moving constantly. So what are these graceful puffs that can both frustrate astronomers and excite photographers simultaneously?

Clouds are frozen ice crystals or white liquid water that you can see with your eyes. Scientists who study clouds go into a field of science called nephology, which is a specialized area of meteorology. Clouds don’t have to be made up of water – they can be any visible puff and can have all three states of matter (solid, liquid, and gas) existing within the cloud formation. For example, Jupiter has two cloud decks: the upper are water clouds, and the lower deck are ammonia clouds.

We’re going to learn how to build a weather instrument that will record whether (weather?) the day was sunny or cloudy using a very sensitive piece of paper. Are you ready?

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Materials:

Sun print paper or other paper sensitive to light
Film canister or soup can
Drill with drill bit
Scissors
Sunlight

The paper from a sun print kit has a very special coating that makes the paper react to light. Most sun print kits use set of light-sensitive chemicals such as potassium ferricyanide and ferric ammonium citrate to make a cyanotype solution. The paper changes color when exposed to UV light. In fact, you can try exposing the paper to different colors and see which changes the paper the most over a set amount of time!

The last step of this chemical process is to ‘set’ the reaction by washing it in plain water – this keeps the image on the paper so it doesn’t all disappear when you hang it on the wall. After the paper dries, the area exposed to UV light turns blue, and everything shaded turns white.

You can use sun print paper to test how well your sunblock works – just smear your favorite sunscreen over a sheet (or put a couple dabs of each kind) and see how well the paper stays protected: if it turns white, the light is getting through. If it stays blue, the sunscreen blocked the light!

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Thermometer

Wednesday June 29, 2011

First invented in the 1600s, thermometers measure temperature using a sensor (the bulb tip) and a scale. Temperature is a way of talking about, measuring, and comparing the thermal energy of objects. We use three different kinds of scales to measure temperature. Fahrenheit, Celsius, and Kelvin. (The fourth, Rankine, which is the absolute scale for Fahrenheit, is the one you’ll learn about in college.)

Mr. Fahrenheit, way back when (18th century) created a scale using a mercury thermometer to measure temperature. He marked 0° as the temperature ice melts in a tub of salt. (Ice melts at lower temperatures when it sits in salt. This is why we salt our driveways to get rid of ice). To standardize the higher point of his scale, he used the body temperature of his wife, 96°.

As you can tell, this wasn’t the most precise or useful measuring device. I can just imagine Mr. Fahrenheit, “Hmmm, something cold…something cold. I got it! Ice in salt. Good, okay there’s zero, excellent. Now, for something hot. Ummm, my wife! She always feels warm. Perfect, 96°. ” I hope he never tried to make a thermometer when she had a fever.

Just kidding, I’m sure he was very precise and careful, but it does seem kind of weird. Over time, the scale was made more precise and today body temperature is usually around 98.6°F.

Later, (still 18th century) Mr. Celsius came along and created his scale. He decided that he was going to use water as his standard. He chose the temperature that water freezes at as his 0° mark. He chose the temperature that water boils at as his 100° mark. From there, he put in 100 evenly spaced lines and a thermometer was born.

Last but not least Mr. Kelvin came along and wanted to create another scale. He said, I want my zero to be ZERO! So he chose absolute zero to be the zero on his scale.

Absolute zero is the theoretical temperature where molecules and atoms stop moving. They do not vibrate, jiggle or anything at absolute zero. In Celsius, absolute zero is -273 ° C. In Fahrenheit, absolute zero is -459°F (or 0°R). It doesn’t get colder than that!

As you can see, creating the temperature scales was really rather arbitrary:

“I think 0° is when water freezes with salt.”
“I think it’s just when water freezes.”
“Oh, yea, well I think it’s when atoms stop!”

Many of our measuring systems started rather arbitrarily and then, due to standardization over time, became the systems we use today. So that’s how temperature is measured, but what is temperature measuring?

Temperature is measuring thermal energy which is how fast the molecules in something are vibrating and moving. The higher the temperature something has, the faster the molecules are moving. Water at 34°F has molecules moving much more slowly than water at 150°F. Temperature is really a molecular speedometer.

Let’s make a quick thermometer so you can see how a thermometer actually works:

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Materials:

plastic bottle
straw
hot glue or clay
water
food coloring
rubbing alcohol
index card and pen

When something feels hot to you, the molecules in that something are moving very fast. When something feels cool to you, the molecules in that object aren’t moving quite so fast. Believe it or not, your body perceives how fast molecules are moving by how hot or cold something feels. Your body has a variety of antennae to detect energy. Your eyes perceive certain frequencies of electromagnetic waves as light. Your ears perceive certain frequencies of longitudinal waves as sound. Your skin, mouth and tongue can perceive thermal energy as hot or cold. What a magnificent energy sensing instrument you are!

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Hygrometer

Wednesday June 29, 2011

Hygrometers measure how much water is in the air, called humidity. If it's raining, it's 100% humidity. Deserts and arid climates have low humidity and dry skin. Humidity is very hard to measure accurately, but scientists have figured out ways to measure how much moisture is absorbed by measuring the change in temperature (as with a sling psychrometer), pressure, or change in electrical resistance (most common).

The dewpoint is the temperature when moist air hits the water vapor saturation point. If the temperature goes below this point, the water in the air will condense and you have fog. Pilots look for temperature and dewpoint in their weather reports to tell them if the airport is clear, or if it''s going to be 'socked in'. If the temperature stays above the dewpoint, then the airport will be clear enough to land by sight. However, if the temperature falls below the dewpoint, then they need to land by instruments, and this takes preparation ahead of time.

A sling psychrometer uses two thermometers (image above), side by side. By keeping one thermometer wet and the other dry, you can figure out the humidity using a humidity chart. Such as the one on page two of this document. The psychrometer works because it measures wet-bulb and dry-bulb temperatures by slinging the thermometers around your head. While this sounds like an odd thing to do, there's a little sock on the bottom end of one of the thermometers which gets dipped in water. When air flows over the wet sock, it measures the evaporation temperature, which is lower than the ambient temperature, measured by the dry thermometer.

Scientists use the difference between these two to figure out the relative humidity. For example, when there's no difference between the two, it's raining (which is 100% humidity). But when there's a 9^oC temperature difference between wet and dry bulb, the relative humidity is 44%. If there's 18^oC difference, then it's only 5% humidity.

You can even make your own by taping two identical thermometers to cardboard, leaving the ends exposed to the air. Wrap a wet piece of cloth or tissue around the end of one and use a fan to blow across both to see the temperature difference!

One of the most precise are chilled mirror dewpoint hygrometers, which uses a chilled mirror to detect condensation on the mirror's surface. The mirror's temperature is controlled to match the evaporation and condensation points of the water, and scientists use this temperature to figure out the humidity.

We're going to make a very simple hygrometer so you get the hand of how humidity can change daily. Be sure to check this instrument right before it rains. This is a good instrument to read once a day and log it in your weather data book.

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Materials:

single hair
index card
tack
cardboard
tape
scissors
dime

This device works because human hair changes length with humidity, albeit small. We magnify this change by using a lever arm (the arrow and mark the different places on the cardboard to indicate levels of humidity. Does all hair behave the same way? Does it matter if you use curly or straight hair, or even the color of the hair? Does gray work better than blonde?

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Anemometer

Wednesday June 29, 2011

Most weather stations have anemometers to measure wind speed or wind pressure. The kind of anemometer we’re going to make is the same one invented back in 1846 that measures wind speed. Most anemometers use three cups, which is not only more accurate but also responds to wind gusts more quickly than a four-cup model.

Some anemometers also have an aerovane attached, which enables scientists to get both speed and direction information. It looks like an airplane without wings – with a propeller at the front and a vane at the back.

Other amemometers don’t have any moving parts – instead they measure the resistance of a very short, thin piece of tungsten wire. (Resistance is how much a substance resists the flow of electrical current. Copper has a low electrical resistance, whereas rubber has a very high resistance.) Resistance changes with the material’s temperature, so the tungsten wire is heated and placed in the airflow. The wind flowing over the wire cools it down and increases the resistance of the wire, and scientists can figure out the wind speed.

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Scientists also use sonic anemometers, which use ultrasonic waves to detect wind speed. The great thing about sonic anemometers is that they can measure speed in all three directions, which is great for studying wind that is not all moving in the same direction (like gusts and hurricanes).

Sonic anemometers send a sound wave from one side to the other and measure the time it takes to travel. Which means that these can also be used as thermometers, as temperature will also change the speed of sound. Since there are no moving parts, you’ll find these types of anemometers in harsh conditions, like on a buoy or in the desert, where salt disintegrates and dust gets in the way of the cup-style anemometer. The big drawback to sonic anemometers is water (like dew or rain): if the transducers get wet, it changes the speed of sound and gives an error in the reading.

The quickest anemometer to make is to attach the end of a string (about 12″ long) to a ping pong ball. Suspend the string in the wind, like from a fan or hair dryer (use the ‘cool’ setting). Since the ball is so lightweight, it’s quite responsive to wind speed.

Add a protractor flipped upside down (so you can measure the angle of the string). Use the measurements below to figure out the wind speed. For example, mark the 90^o angle with “0 mph”. This is your ping pong ball at rest in no wind. Use the numbers below to make the rest:

Angle	Wind Speed
degrees	mph
90	0
80	8
70	12
60	15
50	18
40	21
30	26
20	33

Now let’s make a four-cup anemometer. Here’s what you need to do:

Materials:

four lightweight cups
two sticks or popsicle sticks
tape or hot glue
tack or pin
pencil with eraser on top
block of foam (optional)

How steady was the wind that you measured? If you place your anemometer next to a door or a window, is there wind? How fast? Where could you place your anemometer so you can quickly read it each day?

By making two anemometers, one that you already know what the wind speed is, you can easily figure out how to calibrate the other. For example, how fast do the cups fly around when the ping pong ball anemometer indicates 12 mph? Can you see each cup, or are they a blur? You’ll get a feel for how to read the four-cup model by eye once you’ve had practice.

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Barometer

Wednesday June 29, 2011

French physicist Blaise Pascal. He developed work on natural and applied sciences as well being a skilled mathematician and religious philosopher.

A barometer uses either a gas (like air) or a liquid (like water or mercury) to measure pressure of the atmosphere. Scientists use barometers a lot when they predict the weather, because it’s usually a very accurate way to predict quick changes in the weather.

Barometers have been around for centuries – the first one was in the 1640s!

At any given momen, you can tell how high you are above sea level by measure the pressure of the air. If you measure the pressure at sea level using a barometer, and then go up a thousand feet in an airplane, it will always indicate exactly 3.6 kPa lower than it did at sea level.

Scientists measure pressure in “kPa” which stands for “kilo-Pascals”. The standard pressure is 101.3 kPa at sea level, and 97.7 kPa 1,000 feet above sea level. In fact, every thousand feet you go up, pressure decreases by 4%. In airplanes, pilots use this fact to tell how high they are. For 2,000 feet, the standard pressure will be 94.2 kPa. However, if you’re in a low front, the sea level pressure reading might be 99.8 kPa, but 1000 feet up it will always read 3.6 kPa lower, or 96.2 kPa.

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Materials:

balloon
straw or stick
water glass or clean jam jar
index card
tape

At standard pressure, depending on the kind of barometer you have, you’ll find they all read one of these: 101.3 kPa; 760 mmHg (millimeters of mercury, or “torr”); 29.92 inHg (inches of mercury); 14.7 psi (pounds per square inch); 1013.25 millibars/hectopascal. They are all different unit systems that all say the same thing.

Just like you can have 1 dollar or four quarters or ten dimes or 20 nickels or a hundred pennies, it’s still the same thing.

Why does water boil differently at sea level than it does on a mountain top?

It takes longer to cook food at high altitude because water boils at a lower temperature. Water boils at 212^oF at standard atmospheric pressure. But at elevations higher than 3,500 feet, the boiling point of water is decreased.

The boiling point is defined when the temperature of the vapor pressure is equal to the atmospheric pressure. Think of vapor pressure as the pressure made by the water molecules hitting the inside of the container above the liquid level. But since the saucepan of water is not sealed, but rather open to the atmosphere, the vapor simply expands to the atmosphere and equals out. Since the pressure is lower on a mountaintop than at sea level, this pressure is lower, and hence the boiling point is lowered as well.

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Rain Gauge

Wednesday June 29, 2011

Also known as an udometer or pluviometer or ombrometer, or just plan old ‘rain cup’, this device will let you know how much water came down from the skies. Folks in India used bowls to record rainfall and used to estimate how many crops they would grow and thus how much tax to collect!

These devices reports in “millimeters of rain” or “”centimeters of rain” or even inches of rain”. Sometimes a weather station will collect the rain and send in a sample for testing levels of pollutants.

While collecting rain may seem simple and straightforward, it does have its challenges! Imagine trying to collect rainfall in high wind areas, like during a hurricane. There are other problems, like trying to detect tiny amounts of rainfall, which either stick to the side of the container or evaporate before they can be read on the instrument. And what happens if it rains and then the temperature drops below freezing, before you’ve had a chance to read your gauge? Rain gauges can also get clogged by snow, leaves, and bugs, not to mention used as a water source for birds.

So what’s a scientist to do?

Press onward, like all great scientists! And invent a type of rain gauge that will work for your area. We’re going to make a standard cylinder-type rain gauge, but I am sure you can figure out how to modify it into a weighing precipitation type (where you weigh the amount in the bottle instead of reading a scale on the side), or a tipping bucket type (where a funnel channels the rain to a see-saw that tips when it gets full with a set amount of water) , or even a buried-pit bucket (to keep the animals out).
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Materials:

two water bottles
scissors
rainy day (or use water)

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Desalination

Sunday October 31, 2010

This experiment is for advanced students.

Lewis and Clark did this same experiment when they reached the Oregon coast in 1805. Men from the expedition traveled fifteen miles south of the fort they had built at the mouth of the Columbia River to where Seaside, Oregon now thrives.

In 1805, however, it was just men from the fort and Indians. They built an oven of rocks. For six weeks, they processed 1,400 gallons of seawater, boiling the water off to gain 28 gallons of salt.

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Lewis and Clark National Historic Park commemorates the struggles of the expedition. (The reconstructed fort is also there to visit.) It is Fort Clatsop National Memorial, and is quite an experience to go through the fort.

Lewis and Clark went to great lengths to obtain salt. The men had been complaining that fish without salt had become something to avoid. Salt is important to us as well. It is a condiment, an addition to food that brings out the food’s natural flavor. Besides its food value, salt is used as a food preservative. It destroys bacteria in food by removing moisture from their “bodies” and killing them.

Sodium chloride, table salt, NaCl….they’re all acceptable names for salt. If NaCl is broken down into its component elements, the elements don’t act like our friend salt. Its components are sodium and chlorine.

Sodium is a highly reactive alkali metal, element #11 on the periodic table. It is exothermic in water, which means that is gives of heat as it reacts with water. Small pieces tossed into water will react with it. The sodium particles give off heat that melts them into round balls. The sodium particles bounce and scurry around the surface at a high rate of speed. If you ever get the chance to observe this, do it. The reaction continues until the sodium is gone. Sodium, as it reacts with the water, changes chemically into sodium hydroxide. These cool things that sodium does are also dangerous. Sodium and sodium hydroxide are caustic…they are so pH basic that they will burn you.

Chlorine is a halogen, group 17, element #17. Chlorine is used in bleach, disinfectants, and in swimming pool maintenance. It seems that anywhere you want to remove color or life, chlorine is your element. This property of chlorine to kill was used in war. (It would react with the mucous linings in their throat, undergoing a chemical reaction to turn into hydrochloric acid in their throats. Hydrochloric acid is a very dangerous acid, usually fatal once inside you.) Chlorine is known as bleach at home. Never, never, drink it or breathe its fumes.

Materials:

Goggles
Gloves
Jar or glass
2 90o glass tubes
Chemistry stand
Rubber tubing
Test tube clamp
Erlenmeyer flask
One-hole rubber stopper
Wire screen
Alcohol burner
Lighter
Test tube
Water
Saltwater
Heating rod

Look out for the hot flask and other glassware. Allow everything to cool before cleaning.

When done heating, move the rubber tubing out of the water. There is a difference in pressure between the heated glassware and the water bath. That difference in pressure will cause the water to enter the tubing and cool water will flow into the hot glassware and could cause catastrophic damage to the glassware.

Never…Never!….drink the results of an experiment. Yeah, I know that plain old water is supposed to be in the test tube, but follow the experiment’s safety guidelines. You’ve had other stuff in that test tube, too.

C3000: Experiment 83

Here’s what’s going on in this experiment:

That flask of saltwater will start to boil, and water vapor will leave the flask and travel to the test tube. There is no chemical change occurring in this experiment, but a physical one. A physical change involves a change in state (melting, freezing, vaporization, condensation, sublimation). Physical changes are things like crushing a can, melting an ice cube, breaking a bottle, or boiling saltwater until there is nothing left but salt and steam.

Cleanup: Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids can be washed down the drain

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Convection Currents

Sunday September 5, 2010

Every time I’m served a hot bowl of soup or a cup of coffee with cream I love to sit and watch the convection currents. You may look a little silly staring at your soup but give it a try sometime!

Convection is a little more difficult to understand than conduction. Heat is transferred by convection by moving currents of a gas or a liquid. Hot air rises and cold air sinks. It turns out, that hot liquid rises and cold liquid sinks as well.

Room heaters generally work by convection. The heater heats up the air next to it which makes the air rise. As the air rises it pulls more air in to take its place which then heats up that air and makes it rise as well. As the air get close to the ceiling it may cool. The cooler air sinks to the ground and gets pulled back near the heat source. There it heats up again and rises back up.

This movement of heating and cooling air is convection and it can eventually heat an entire room or a pot of soup. This experiment should allow you to see convection currents.

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You need:

A pot
A stove with adult help
Pepper
Ice cubes
Food Coloring (optional)

1. Fill the pot about half way with water.

2. Put about a teaspoon of pepper into the water.

3. Put the pot on the stove and turn on the stove (be careful please).

4. Watch as the water increases in temperature. You should see the pepper moving. The pepper is moving due to the convection currents. If you look carefully you many notice pepper rising and falling.

5. Put an ice cube into the water and see what happens. You should see the pepper at the top of the water move towards the ice cube and then sink to the bottom of the pot as it is carried by the convection currents.

6. Just for fun, put another ice cube into the water, but this time drop a bit of food coloring on the ice cube. You should see the food coloring sink quickly to the bottom and spread out as it is carried by the convection currents.

Did you see the convection currents? Hot water rising in some areas of the pot and cold water sinking in other areas of the pot carried the pepper and food coloring throughout the pot. This rising and sinking transferred heat through all the water causing the water in the pot to increase in temperature.

Heat was transferred from the flame of the stove to the water by convection. More accurately, heat was transferred from the flame of the stove to the metal of the pot by conduction and then from the metal of the pot throughout the water through convection.

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Sensing Temperature

Sunday September 5, 2010

Temperature is a way of talking about, measuring, and comparing the thermal energy of objects.

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The words “hot” , “cold”, “warm” and so forth describe what scientists call thermal energy. Thermal energy is how much the molecules are moving inside an object. The faster molecules move, the more thermal energy it has.

Objects that have molecules moving very quickly are said to have high thermal energy or high temperature. Like a cloud of steam, for example. The higher the temperature, the faster the molecules are moving inside that steam cloud.

Temperature is just a speedometer for molecules. The speed of the molecules in ice cream is way slower than it is in a hot shower.

If everything is made of molecules, and these molecules are speeding up and slowing down, what do you think happens if they change speed a lot? Do you think my kitchen table will start vibrating across the room if the table somehow gets too hot?

No, probably not, my table will not start jumping around the room, no matter how hot it gets. It would melt down into a mush first! But some interesting things do happen when molecules change speeds.

There are three common states of matter – I bet you know what they are already: solid, liquid, and gas. Water is really special because it can a solid, liquid or gas state pretty normal temperatures. You don’t need a mad scientist lab to get it to go into any of these three states.

Water is one of the only substances that expands instead of shrinks when it freezes. It’s also a polar molecule, meaning that if you stick a static charge next to it, like a balloon you rubbed on your head, you can get the water to move.

Imagine an icicle. The water is in a solid state when it’s an icicle. It’s holding its shape. The molecules in the water are held together by strong, stiff bonds. These bonds hold the water molecules in a tight pattern called a matrix. This matrix holds the water molecules in a crystalline pattern.

Can you imagine breaking off an icicle and sticking it in a tea kettle on the stove? Now, let’s pretend to turn on the heat. The heat is transferred from the stove to the kettle to the icicle.

What happens to our icicle?

As the icicle absorbs the heat, the molecules begin to vibrate faster (the temperature is increasing). When the molecules vibrate at a certain speed (they gain enough thermal energy) they stretch those strong, stiff matrix crystalline bonds enough that the bonds become more like rubber bands or springs and they stretch and get all loose-goosey.

That’s when the icicle becomes liquid. There are still bonds between the molecules, but they are a bit loose, allowing the molecules to move and flow around each other.

The act of changing from a solid to a liquid is called melting. The temperature at which a substance changes from a solid to a liquid is called its melting point. For water, that point is 32° F or 0° C. (Remember those numbers from the slide with all the temperature scales?)

Now if we continue heating, we see our icicle go from solid to completely liquid, and now we notice bubbling. What’s going on now?

Now the temperature is at 212° F or 100° C and the water is going from a liquid state to a gaseous state. This means that the loosey goosey bonds that connected the molecules before have been stretched as far as they go, can’t hold on any longer and “POW!” they snap.

Those water molecules no longer have any bonds and are free to roam aimlessly around the room (think toddlers). Gas molecules move at very quick speeds as they bounce, jiggle, crash and zip around any container they are in (kind of like toddles on sugar). The act of changing from a liquid to a gas is called evaporation or boiling and the temperature at which a substance changes from a liquid to a gas is called its boiling point.

Now if we turn off the stove, what do you think happens?

Our gaseous water molecules get close to something cool, they will combine and turn from gaseous to liquid state. This is what happens to your bathroom mirror during a shower or bath. The gaseous water molecules that are having fun bouncing and jiggling around the bathroom get close to the mirror. The mirror is colder than the air. As the gas molecules get close they slow down due to loss of temperature. If they slow enough, they form loosey goosey bonds with other gas molecules and change from gas to liquid state.

The act of changing from gas to liquid is called condensation. The temperature at which molecules change from a gas to a liquid is called the condensation point. Clouds are made of hundreds of billions of tiny little droplets of liquid water that have condensed onto particles of some sort of dust.

Now let’s turn the heat down a bit more and see what happens. Imagine we stick the tea kettle in the freezer. As the temperature drops and the molecules continue to slow, the bonds between the molecules can pull them together tighter and tighter.

Eventually the molecules will fall into a matrix, a pattern, and stick together quite tightly. This would be the solid state. The act of changing from a liquid to a solid is called freezing and the temperature at which it changes is called (say it with me now) freezing point.

Think about this for a second – is the freezing point and melting point of an object at the same temperature? Does something go from solid to liquid or from liquid to solid at the same temperature?

If you said yes, you’re right!

The freezing point of water and the melting point of water are both 32° F or 0° C. The temperature is the same. It just depends on whether it is getting hotter or colder as to whether the water is freezing or melting.

The boiling and condensation point is also the same point.

Crazy Temperatures

Here’s an experiment you can do to baffle your senses: Fill one glass with hot water (not boiling), another with ice water, and a third with room temperature water. Place a finger in the hot water and a finger in the ice cold water for a minute or two. Then stick both fingers in the room temperature cup.

How does that feel?

Did it seem that each finger detected a different temperature when placed in the room temperature cup? Weird! So what gives?

Materials:

3 cups of water (see video)
your hands

Download Student Worksheet & Exercises

Your skin contains temperature sensors that work by detecting the direction heat flow (in or out of your body), not temperature directly. These sensors change temperature depending on their surroundings. So when you heated up one finger, and then placed it in cooler water, the heat flowed out of your body, telling your brain it was getting cooler. The ice water finger was detecting a heat flow into your body… and presto! You have one confused brain.

In order for heat to flow, you need to have a temperature difference. Did you notice how your fingers weren’t good thermometers with this experiment? This is why scientists had to invent the thermometer, because the human body isn’t designed to detect temperature, only heat flow.

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Food Dye Currents

Sunday September 5, 2010

Let’s find out how to watch the hot and cold currents in water. Here’s what you need to do:

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Materials:

two bottles of water
food coloring
bathtub or sink
index card or business card

You need:

Two empty bowls (or water bottles)
Food coloring
Hot water (Does not need to be boiling.)
Cold water

1. Put about the same amount of water into two bowls. One bowl should be filled with hot water from the tap. If you’re careful, you can put it in the microwave to heat it up but please don’t hurt yourself. The other bowl should have cold water in it. If you’re using water bottles, pour the hot and cold water into each bottle.

2. Let both bowls sit for a little bit (a minute or so) so that the water can come to rest.

3. Put food coloring in both bowls (or bottles) and watch carefully.

The food coloring should have spread around faster in the hot water bowl than in the cold water bowl. Can you see why? Remember that both bowls are filled with millions and millions of molecules. The food coloring is also bunches of molecules. Imagine that the molecules from the water and the molecules from the food coloring are crashing into one another like the beans on the plate. If one bowl has a higher temperature than the other, does one bowl have faster moving molecules? Yes, the higher temperature means a higher thermal energy. So the bowl with the warmer water has faster moving molecules which crash more and harder with the food coloring molecules, spreading them faster around the bowl.

If you’re using a bottle, you can do an extra step: For bottles, place a business card over the cold bottle and invert the cold bottle over the hot. Remove card.

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Making Clouds

Sunday September 5, 2010

Indoor Rain Clouds

Making indoor rain clouds demonstrates the idea of temperature, the measure of how hot or cold something is. Here’s how to do it:

Take two clear glasses that fit snugly together when stacked. (Cylindrical glasses with straight sides work well.)

Fill one glass half-full with ice water and the other half-full with very hot water (definitely an adult job – and take care not to shatter the glass with the hot water!). Be sure to leave enough air space for the clouds to form in the hot glass.

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Place the cold glass directly on top of the hot glass and wait several minutes. If the seal holds between the glasses, a rain cloud will form just below the bottom of the cold glass, and it actually rains inside the glass! (You can use a damp towel around the rim to help make a better seal if needed.)

Materials:

glass of ice water
glass of hot water (see video)
towel
adult help

Download Student Worksheet & Exercises

Bottling Clouds

On a stormy, rainy afternoon, try bottling clouds — using the refrigerator! Here’s what you do: Place an empty, clean 2-liter soda bottle in the fridge overnight. Take it out and get an adult to light a match, letting it burn for a few seconds, then drop it into the bottle. Immediately cap the bottle and watch what happens (you should see smoke first, then clouds forming inside). Squeeze the sides of the bottle. The clouds should disappear. When you release the bottle, the clouds should reappear. Materials:

2L soda bottle
rubbing alcohol
bicycle pump
car tire valve (drill a 1/2 inch hole through a 2L soda bottle cap and pull the valve gently through with pliers)

Advanced Idea: You can substitute rubbing alcohol and a bicycle pump for the matches to make a more solid-looking cloud. Swirl a bit of rubbing alcohol around inside the bottle, just enough to coat the insides, and then pour it out. Cap your bottle with a rubber stopper fitted with a needle valve (so the valve is poking out of the bottle), and apply your pump. Increase the pressure inside the bottle (keep a firm hand on the stopper or you’ll wind up firing it at someone) with a few strokes and pull out the stopper quickly. You should see a cloud form inside.

What’s going on? Invisible water vapor is all around us, all the time, but they normally don’t stick together. When you squeezed the sides of the bottle, you increased the pressure and squeezed the molecules together. Releasing the bottle decreases the pressure, which causes the temperature to drop. When it cools inside, the water molecules stick to the smoke molecules, making a visible cloud inside your bottle.

Did you know that most drops of water actually form around a dust particle? Up in the sky, clouds come together when water vapor condenses into liquid water drops or ice crystals. The clouds form when warm air rises and the pressure is reduced (as you go up in altitude). The clouds form at the spot where the temperature drops below the dew point.

The alcohol works better than the water because it evaporates faster than water does, which means it moves from liquid to vapor more easily (and vividly) than regular old water.

Questions to ask:

How many times can you repeat this?
Does it matter what size the bottle is?
What if you don’t chill the bottle?
What if you freeze the bottle instead?

Exercises

Which combination made it rain the best? Why did this work?
Draw your experimental diagram, labeling the different components:
Add in labels for the different phases of matter. Can you identify all three states of matter in your experiment?

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Soaking Up Rays

Sunday September 5, 2010

Heat is transferred by radiation through electromagnetic waves. Remember, when we talked about waves and energy? Well, heat can be transferred by electromagnetic waves. Energy is vibrating particles that can move by waves over distances right? Well, if those vibrating particles hit something and cause those particles to vibrate (causing them to move faster/increasing their temperature) then heat is being transferred by waves. The type of electromagnetic waves that transfer heat are infra-red waves. The Sun transfers heat to the Earth through radiation.

If you hold your hand near (not touching) an incandescent light bulb until you can feel heat on your hand, you’ll be able to understand how light can travel like a wave. This type of heat transfer is called radiation.

Now don’t panic. This is not a bad kind of radiation like you get from x-rays. It’s infra-red radiation. Heat was transferred from the light bulb to your hand. The energy from the light bulb resonated the molecules in your hand. (Remember resonance?) Since the molecules in your hand are now moving faster, they have increased in temperature. Heat has been transferred! In fact, an incandescent light bulb gives off more energy in heat then it does in light. They are not very energy efficient.

Now, if it’s a hot sunny day outside, are you better off wearing a black or white shirt if you want to stay cool? This experiment will help you figure this out:

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You need:

2 ice cubes, about the same size.
A white piece of paper
A black piece of paper
A sunny day

Download Student Worksheet & Exercises

1. Put the two pieces of paper on a sunny part of the sidewalk.

2. Put the ice cubes in the middle of the pieces of paper.

3. Wait.

What you should eventually see, is that the ice cube on the black sheet of paper melts faster then the ice cube on the white sheet. Dark colors absorb more infra-red radiation then light colors. Heat is transferred by radiation easier to something dark colored then it is to something light colored and so the black paper increased in temperature more then the white paper.

So, to answer the shirt question, a white shirt reflects more infra-red radiation so you’ll stay cooler. White walls, white cars, white seats, white shorts, white houses, etc. all act like mirrors for infra-red (IR) radiation. Which is why you can aim your TV remote at a white wall and still turn on the TV. Simply pretend the wall is a mirror (so you can get the angle right) and bounce the beam off the wall before it gets to your TV. It looks like magic!

Click over to this experiment to learn how to make Liquid Crystals.

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Liquid Crystals

Sunday September 5, 2010

If you’ve completed the Soaking Up Rays experiment, you might still be a bit baffled as to why there’s a difference between black and white. Here’s a great way to actually “see” radiation by using liquid crystal thermal sheets.

You’ll need to find a liquid crystal sheet that has a temperature range near body temperature (so it changes color when you warm it with your hands.)

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The liquid crystal sheet is temperature-sensitive. When the sheet received heat from the bulb, the temperature goes up and changes color. The plastic sheets remain black except for the temperature range in which they display a series of colors that reflect the actual temperature of the crystal.

Materials:

hands
Thermal paper (AKA: Liquid Crystal Sheet)
Incandescent light bulb (or sunny day)
Silver highlighter or aluminum foil

1. Color half of the back side of the thermal paper (the side that doesn’t change color) with the highlighter (or cover half of it with foil).

2. Hold it in a position where you can easily see the color-changing side while keeping the light source on the back side.

3. Which side changes color? Is there a difference between the silver and black halves?

You’ll notice that the black half almost immediately changes color, while the silver side stays black. The silver coating reflects the heat, keeping it cool. The black side absorbs the heat and raises its temperature.

Why do liquid crystals change color with temperature? Your liquid crystal sheet is not just one sheet, but a stack of several sheets that are slightly offset from each other. The distance between each layer changes as the sheet warms up – the hotter the temperature, the closer the stacks twist together. The color they emit depends on the distance between the sheets.

The molecules that make up the sheets are long and thin, like hot dogs. When the sheets are cooler, these molecules move around less and don’t twist up as much, which corresponds to reflecting back a redder light. When the temperature rises, the molecules move around more and twist together, and they reflect a bluer light. When the liquid crystal sheet is black, all the light is absorbed (no light gets reflected).

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Water Purification

Wednesday June 30, 2010

Ever wonder how the water draining down your sink gets clean again? Think about it: The water you use to clean your dishes is the same water that runs through the toilet. There is only one water pipe to the house, and that source provides water for the dishwasher, tub, sink, washing machine, toilet, fish tank, and water filter on the front of your fridge. And there’s only one drain from your house, too! How can you be sure what’s in the water you’re using?

This experiment will help you turn not only your coffee back into clear water, but the swamp muck from the back yard as well. Let’s get started.
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clean play sand
alum (check the spice section of the grocery store)
distilled water
water sample (a cup of coffee with the ground put back in works great)
activated carbon (check an aquarium store)
cheese cloth
clear disposable cups
popsicles
medicine dropper or syringe (no needle)
funnel
2 cotton balls
measuring spoon (1/4 tsp and 1/2 tsp)

Download Student Worksheet & Exercises

There are several steps you need to understand as we go along:

Aeration: Aerate water to release the trapped gas. You do this in the experiment by pouring the water from one cup to another.
Coagulation: Alum collects small dirt particles, forming larger, sticky particles called floc.
Sedimentation: The larger floc particles settle to the bottom of the cup.
Filtration: The smaller floc particles are trapped in the layer of sand and cotton.
Disinfection: A small amount of disinfectant is added to kill the remaining bacteria. This is for informational purposes only — we won’t be doing it in this experiment. (Bleach and kids don’t mix!)

Preparing the Sample

Make your “swamp muck” sample by filling a small pitcher with water, coffee, and the coffee grounds. Fill up another small pitcher with clean water. In a third small pitcher, pour a small scoop of charcoal carbon and cold water.

Fill one clear plastic cup half full of swamp muck. Stir in ½ teaspoon aluminum sulfate (also known as alum) and ¼ teaspoon calcium hydroxide (also known as lime; it’s nasty stuff to breathe in so keep it away from kids). You have just made floc, the heavy stuff that settles to the bottom.

Aside: For pH balance, you can add small amounts of lime to raise the pH (level 7 is optimal), if you have pH indicators on hand (find these at the pharmacy).

Stir it up and sniff — then don’t touch for 10 minutes as you make the filter.

Making the Filter

Grab a cotton ball and fluff it out HUGE. Then stuff it into the funnel. The funnel will take two or three balls. (Don’t stuff too hard, or nothing will get through!) Strain out the carbon granules from the pitcher, and put the black carbon water back into the pitcher. Place the funnel over a clean cup and pour the black water directly over the cotton balls. Run the dripped-out water back through the funnel a few times. Those cotton balls will turn gray-black! Discard all the carbon water.

Add a layer of sand over the top of the cotton balls. It should cover the balls entirely and come right up to the top of the funnel. Fill a third empty cup half-full of clean water from the pitcher. Drip (using a dropper) clean water into the funnel. (This gets the filter saturated and ready to filter.)

Showtime!

It’s time to filter the swamp muck. Without disturbing the sample, notice where the floc is… the dark, solid layer at the bottom. You’ve already filtered out the larger particles without using a filter! Using a dropper, take a sample from the layer above the floc (closer to the top of your container) and drip it into the funnel. If you’ve set up your experiment just right, you’ll see clear water drip out of your funnel.

Continue this process until the liquid starts to turn pale – which indicates that your filter is saturated and can’t filter out any more particles.

To dissect the filter and find out where the muck got trapped, invert the funnel over four layers of paper towel. Usually the blacker the cotton, the better the filter will work. Look for coffee grounds in the sand.

“Radioactive” Sample

Activate a disposable light stick. Break open the light stick (use gloves when handling the inner liquid), and using the dropper, add the liquid to the funnel. You can also drip the neon liquid by the drop into the swamp muck sample and pass it through your filter.

You can test out other types of “swamp muck” by mixing together other liquids (water, orange juice, etc.) and solids (citrus pulp, dirt, etc.). Stay away from carrot juice, grape juice, and beets — they won’t work with this type of filter.

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Streaming Water

Tuesday June 1, 2010

Fill the bathtub and climb in. Grab your water bottle and tack and poke several holes into the lower half the water bottle. Fill the bottle with water and cap it. Lift the bottle above the water level in the tub and untwist the cap. Water should come streaming out. Close the cap and the water streams should stop. Open the cap and when the water streams out again, can you “pinch” two streams together using your fingers?

Materials: A tack, and a plastic water bottle with cap, and bathtub

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What’s happening? First, you’re getting clean. Second, you’re playing with pressure again. Watch the water level when you uncap the bottle. As the water streams out, the water level in the bottle moves downward. Notice how the space for air increases in the top of the bottle as the water line moves down. (The air comes in through the mouth of the bottle.) When you cap on the bottle, there’s no place for air to enter the bottle. The water line wants to move down, but since there’s no incoming air to equalize the pressure, the flow of water through the holes stops. Technically speaking, there’s a small decrease in pressure in the air pocket in the top of the bottle and therefore the air outside the bottle has a higher pressure that keeps the water in the bottle. Higher pressure pushes!

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Sneaky Bottles

Tuesday June 1, 2010

This experiment illustrates that air really does take up space! You can’t inflate the balloon inside the bottle without the holes, because it’s already full of air. When you blow into the bottle with the holes, air is allowed to leak out making room for the balloon to inflate. With the intact bottle, you run into trouble because there’s nowhere for the air already inside the bottle to go when you attempt to inflate the balloon.

You’ll need to get two balloons, one tack, and two empty water bottles.

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Poke a balloon into a water bottle and stretch the balloon’s neck covering the mouth of the bottle from the inside. Repeat with the other bottle. Using the tack, poke several small holes in the bottom of one of the water bottles. Putting your mouth to the neck of each bottle, try to inflate the balloons.

A cool twist on this activity is to drill a larger hole in the bottle (say, large enough to be covered up by your thumb) and inflate the balloon inside the bottle with hole open, then plug up the hole with your thumb. The balloon will remain inflated even though its neck is not tied! Where is the higher pressure region now?

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Squished Balloon

Tuesday June 1, 2010

Fire eats air, or in more scientific terms, the air gets used up by the flame and lowers the air pressure inside the jar. The surrounding air outside the jar is now at a higher pressure than the air inside the jar and it pushes the balloon into the jar. Remember: Higher pressure pushes!

Materials: a balloon, one empty glass jar, scrap of paper towel , matches with an adult

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Blow up a balloon so that it is just a bit larger than the opening of the jar and can’t be easily shoved in. With an adult, light the small wad of paper towel on fire and drop it into the jar. Place the balloon on top. When the fire goes out, lift the balloon. The jar goes with it!

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Fountain Bottle

Tuesday June 1, 2010

As you blow air into the bottle, the air pressure increases inside the bottle. This higher pressure pushes on the water, which gets forced up and out the straw (and up your nose!).

Materials: small lump of clay, water, a straw, and one empty 2-liter soda bottle.

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Fill a 2-liter soda water bottle full of water and seal it with a lump of clay wrapped around a long straw so that the straw is secured to the mouth of the bottle. (The straw should be partly submerged in the water.) Blow hard into the straw. Splash!

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Ping Pong Funnel

Monday May 31, 2010

As you blow into the funnel, the air under the ball moves faster than the other air surrounding the ball, which generates an area of lower air pressure. The pressure under the ball is therefore lower than the surrounding air which is, by comparison, at a higher pressure. This higher pressure pushes the ball back into the funnel, no matter how hard you blow or which way you hold the funnel. The harder you blow, the more stuck the ball becomes. Cool.

Materials: A funnel and a ping pong ball

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Insert a ping pong ball into a funnel. Place the stem of the funnel between your lips and tilt your head back so ball stays inside. Blow a strong, long stream of air into the funnel.

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Magic Water Glass Trick

Monday May 31, 2010

Where’s the pressure difference in this trick?

At the opening of the glass. The water inside the glass weighs a pound at best, and, depending on the size of the opening of the glass, the air pressure is exerting 15-30 pounds upward on the bottom of the card. Guess who wins? Tip, when you get good at this experiment, try doing it over a friend’s head!

Materials: a glass, and an index card large enough to completely cover the mouth of the glass.

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Fill a glass one-third with water. Cover the mouth with an index card and over a sink invert the glass while holding the card in place. Remove your hand from the card. Voila! Because atmospheric air pressure is pushing on all sides of both the glass and the card, the card defies gravity and “sticks” to the bottom of the glass. Recall that higher pressure pushes and when you have a difference in pressure, things move. This same pressure difference causes storms, winds, and the index card to stay in place.

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Hot Air Balloon

Monday May 31, 2010

About 400 years ago, Leonardo da Vinci wanted to fly… so he studied the only flying things around at that time: birds and insects. Then he did what any normal kid would do—he drew pictures of flying machines!

Centuries later, a toy company found his drawing for an ornithopter, a machine that flew by flapping its wings (unlike an airplane, which has non-moving wings). The problem (and secret to the toy’s popularity) was that with its wing-flapping design, the ornithopter could not be steered and was unpredictable: It zoomed, dipped, rolled, and looped through the sky. Sick bags, anyone?

Hot air balloons that took people into the air first lifted off the ground in the 1780s, shortly after Leonardo da Vinci’s plans for the ornithopter took flight. While limited seating and steering were still major problems to overcome, let’s get a feeling for what our scientific forefathers experienced as we make a balloon that can soar high into the morning sky.

Materials: A lightweight plastic garbage bag, duct or masking tape, a hand-held hair dryer. And a COLD morning.

Here’s what you do:

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Shake out a garbage bag to its maximum capacity. Using duct or masking tape, reduce the opening until it is almost-closed leaving only a small hole the size of the hair dryer nozzle. Use the hair dryer to inflate the bag, heating the air inside, but make sure you don’t melt the bag! When the air is at its warmest, release your hold on the bag while at the same time you switch off the hair dryer. The bag should float upwards and stay there for a while.

Troubleshooting: This experiment works best on cold, windless mornings. If it’s windy outside, try a cool room. The greater the temperature difference between the hot air inside the garbage bag versus the cold, still air, the faster the bag rises. The only other thing to watch for is that you’ve taped the mouth of the garbage bag securely so the hot air doesn’t seep out. Be sure the opening you leave is only the diameter of your hair dryer’s nozzle.

Want to go BIGGER? Then try the 60-foot solar tube!
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Diaper Wind Bag

Monday May 31, 2010

Lots of science toy companies will sell you this experiment, but why not make your own? You’ll need to find a loooooong bag, which is why we recommend a diaper genie. A diaper genie is a 25′ long plastic bag, only both ends are open so it’s more like a tube. You can get three 8-foot bags out of one pack.

Kids have a tendency to shove the bag right up to their face and blow, cutting off the air flow from the surrounding air into the bag. When they figure out this experiment and perform it correctly, this is one of those oooh-ahhh experiments that will leave your kids with eyes as big as dinner plates.

Here’s what you do:

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Cut an eight-foot section of the diaper genie bag and knot one of the ends. Hold the other end open, take a deep breath, and blow. How many breaths does it take for you to fill up the entire bag with air? Try this now…

After you know how many breaths it takes, do you think you can fill the bag with only ONE breath? The answer is YES! Hold the bag about eight inches from the face and blow long and steady into the bag. As soon as you run out of air, close the end of the bag and slide your hand along the length (toward the knotted end) until you have an inflated blimp.

Troubleshooting: If the bag tears open, use packing tape to mend it.

What’s going on? When you blow air past your lips, a pocket of lower air pressure forms in front of your face. The stronger you blow, the lower the air pressure pocket. The air surrounding this lower pressure region is now at a higher pressure than the surrounding air, which causes things to shift and move. When you blow into the bag (keeping the bag a few inches from your face), you build a lower pressure area at the mouth of the bag, and the surrounding air rushes forward and into the bag.

Substitution Tip: If you can’t locate a diaper genie, you can string together plastic sheets from garbage bags, using lightweight tape to secure the seams. You’ll need to make a 8-12” diameter by eight-foot long tube and close one end. When kids get their eight-foot bag inflated in just one breath, ask them: “Did you really have that much air in your lungs?”

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Genie in a Bottle

Monday May 31, 2010

While this isn’t actually an air-pressure experiment but more of an activity in density, really, it’s still a great visual demonstration of why Hot Air Balloons rise on cold mornings.

Imagine a glass of hot water and a glass of cold water sitting on a table, side by side. Now imagine you have a way to count the number of water molecules in each glass. Which glass has more water molecules?

The glass of cold water has way more molecules… but why? The cold water is more dense than the hot water. Warmer stuff tends to rise because it’s less dense than colder stuff and that’s why the hot air balloon in experiment 1.10 floated up to the sky.

Clouds form as warm air carrying moisture rises within cooler air. As the warm, wet air rises, it cools and begins to condense, releasing energy that keeps the air warmer than its surroundings. Therefore, it continues to rise. Sometimes, in places like Florida, this process continues long enough for thunderclouds to form. Let’s do an experiment to better visualize this idea.

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Materials: Two identical tall glasses, hot water, cold water, red and blue food dye, and an index card larger enough to cover the opening of the glasses

Fill two identical water glasses to the brim: one with hot water, the other with cold water. Put a few drops of blue dye in the cold water, a few drops of red dye in the hot water. Place the index card over the mouth of the cold water and invert the glass over the glass of hot water. Line up the openings of both glasses, and slowly remove the card.

Troubleshooting: Always invert the cold glass over the hot glass using an index card to hold the cold water in until you’ve aligned both glasses. You can also substitute soda bottles for water glasses and slide a washer between the two bottles to decrease the flow rate between the bottles so the effect lasts longer.

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Soda Can Trick

Monday May 31, 2010

When air moves, the air pressure decreases. This creates a lower air pressure pocket right between the cans relative to the surrounding air. Because higher pressure pushes, the cans clink together. Just remember – whenever there’s a difference in pressure, the higher pressure pushes.

You will need about 25 straws and two empty soda cans or other lightweight containers

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Lay a row of straws parallel to each other on a smooth tabletop. Place two empty soda cans on the straws about an inch apart. Lower your nose to the cans and blow hard through the space between the two cans.

Clink! They should roll toward each other and touch!

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Air Takes Space

Monday May 31, 2010

You’re about to play with one of the first methods of underwater breathing developed for scuba divers hundreds of years ago.! Back then, scientists would invert a very large clear, bell-shaped jar over a diver standing on a platform, then lower the whole thing into the water. Everyone thought this was a great idea, until the diver ran out of breathable air…

Materials: 12″ flexible tubing, two clear plastic cups, bathtub

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Part I: Fill the tub and climb in. Plunge one cup underwater so it fills completely with water. While the cup is underwater, point its mouth downward. Insert one end of the tubing into the cup and blow hard into the other end. The water is forced out of the cup!

Part II: While still in the tub, invert one cup (mouth downwards) and plunge it into the tub so that air gets trapped inside the cup. Place the second cup in the water so it fills with water. Invert the water-filled cup while underwater and position it above the first cup so when you tilt the first cup to release the air bubbles, they get trapped inside the second cup. Here you see that air takes space, because in both variations of this experiment the air forced the water out of the cups.

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Squished Soda Can

Sunday January 31, 2010

An average can of soda at room temperature measures 55 psi before you ever crack it open. (In comparison, most car tires run on 35 psi, so that gives you an idea how much pressure there is inside the can!)

If you heat a can of soda, you’ll run the pressure over 80 psi before the can ruptures, soaking the interior of your house with its sugary contents. Still, you will have learned something worthwhile: adding energy (heat) to a system (can of soda) causes a pressure increase. It also causes a volume increase (kaboom!).
How about trying a safer variation of this experiment using water, an open can, and implosion instead of explosion?

Materials – An empty soda can, water, a pan, a bowl, tongs, and a grown-up assistant.

NOTE: If you can get a hold of one, use a beer can – they tend to work better for this experiment. But you can also do this with a regular old soda can. And no, I am not suggesting that kids should be drinking alcohol! Go ask a parent to find you one – and check the recycling bin.

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Prepare an ice bath by putting about ½” of ice water in a shallow dish. With an adult, place a few tablespoons of water in an empty soda or beer can and place the can upright in a skillet on the stove. When the can emits a think trickle of steam, grab the can with tongs and quickly invert it into the ice dish. CRACK!

Troubleshooting: The trick to making this work is that the can needs to be full of hot steam, which is why you only want to use a tablespoon or two of water in the bottom of the can. It’s alright if a bit of water is still at the bottom of the can when you flip it into the ice bath. In fact, there should be some water remaining or you’ll superheat the steam and eventually melt the can. You want enough water in the ice bath to completely submerge the top of the can.

Always use tongs when handling the heated can and make sure you completely submerge the top of the can in the icy water. The water needs to seal the hole in the top of the can so the steam doesn’t escape. Be prepared for a good, loud CRACK! when you get it right.

Why does this work? By heating up the water in the can, you’re changing the state of water from a liquid to a has (called water vapor), which drives out the air, leaving the steam inside. When inverted and cooled, the steam condenses to a small volume of liquid water (much smaller than if it was just hot air). The molecules in water vapor are a lot further apart than when they are in a liquid state. Since the air inside the can has been replaced by the steam, when it cools quickly, it creates a lower air pressure region in the can, so the air pressure surrounding the outside of the can rapidly crushes the can.

If you look really carefully as it condenses, you’ll see cold water from the bowl zoom into the can, just like when you suck water through a straw. The vacuum created int he can by the condensing steam creates a lower pressure, which pushes water into the can itself. When you suck from a straw, you’re creating a lower air pressure region in your mouth so that the surrounding air pressure pushes liquid up the straw to equalize the pressure.

Remember, high pressure always pushes!

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Can Fish Drown?

Sunday January 10, 2010

If you’ve ever owned a fish tank, you know that you need a filter with a pump. Other than cleaning out the fish poop, why else do you need a filter? (Hint: think about a glass of water next to your bed. Does it taste different the next day?)

There are tiny air bubbles trapped inside the water, and you can see this when you boil a pot of water on the stove. The experimental setup shown in the video illustrates how a completely sealed tube of water can be heated… and then bubbles come out one end BEFORE the water reaches a boiling point. The tiny bubbles smoosh together to form a larger bubble, showing you that air is dissolved in the water.

Materials:

test tube clamp
test tube
lighter (with adult help)
alcohol burner or votive candle
right-angle glass tube inserted into a single-hole stopper
regular tap water

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Download Student Worksheet & Exercises

The filter pump in your fish tank ‘aerates’ the water. The simple act of letting water dribble like a waterfall is usually enough to mix air back in. Which is why flowing rivers and streams are popular with fish – all that fresh air getting mixed in must feel good! The constant movement of the river replaces any air lost and the fish stay happy (and breathing). Does it make sense that fish can’t live in stagnant or boiled water?

You don’t need the fancy equipment show in this video to do this experiment… it just looks a lot cooler. You can do this experiment with a pot of water on your stove and watch for the tiny bubbles before the water reaches 212^oF.

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Rock Candy Crystals

Friday October 2, 2009

Crystals are formed when atoms line up in patterns and solidify. There are crystals everywhere — in the form of salt, sugar, sand, diamonds, quartz, and many more!

To make crystals, you need to make a very special kind of solution called a supersaturated solid solution. Here’s what that means: if you add salt by the spoonful to a cup of water, you’ll reach a point where the salt doesn’t disappear (dissolve) anymore and forms a lump at the bottom of the glass.

The point at which it begins to form a lump is just past the point of saturation. If you heat up the saltwater, the lump disappears. You can now add more and more salt, until it can’t take any more (you’ll see another lump starting to form at the bottom). This is now a supersaturated solid solution. Mix in a bit of water to make the lump disappear. Your solution is ready for making crystals. But how?

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Here’s what you need:

pencil or wooden skewer
string
glass jar (cleaned out pickle, jam or may jars work great)
8 cups of sugar
3 cups water
paper clip
adult help and a stove
food coloring is optional but fun!

If you add something for the crystals to cling to, like a rock or a stick, crystals can grow. If you “seed” the object (coat it with the stuff you formed the solution with, such as salt or sugar), they will start forming faster. If you have too much salt (or other solid) mixed in, your solution will crystallize all at the same time and you’ll get a huge rock that you can’t pull out of the jar. If you have too little salt, then you’ll wait forever for crystals to grow. Finding the right amount takes time and patience.

Download Student Worksheet & Exercises

1. If you plan on eating the sugar crystal when you’re done you probably want to boil water with the jar and the paper clip in it to get rid of any nasties. Be careful, and don’t touch them while they are hot.

2. Tie one end of the string to the pencil and the opposite end to the paper clip. (You can alternatively use a skewer instead of a piece of string to make it look more like the picture above, but you’ll need to figure out a way to suspend the skewer in the jar without touching the sides or bottom of the jar.)

3. Wet the string a bit and roll it in some sugar. This will help give the sugar crystals a place to start.

4. Place the pencil across the top of the jar. Make sure the clip is at the bottom of the jar and that the string hangs straight down into the jar. Try not to let the sting touch the side of the jar.

5. Heat 3 cups of water to a boil

6. Dissolve 8 cups of sugar in the boiling water (again be careful!). Stir as you add. You should be able to get all the sugar to dissolve. You can add more sugar until you start to see undissolved bits at the bottom of the pan. If this happens, just add a bit of water until they disappear.

7. Feel free to add some food coloring to the water.

8. Pour the sugar water into the jar. Put the whole thing aside in a quiet place for 2 days to a week. You may want to cover the jar with a paper towel to keep dust from getting in.

You should see crystals start to grow in about 2 days. They should get bigger and bigger over the few days. Once you’re happy with how big your crystals get, you can eat them! It’s nothing but sugar! (Be sure to brush your teeth!) This one (left) us about 6 months old.

There you go! Next time you hold a pencil, throw a ball, or put on a shoe try to keep in mind that what you’re doing is using an object that is made of tiny strange atoms all held tightly together by their bonds.

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Penny Crystal Structure

Friday October 2, 2009

The atoms in a solid, as we mentioned before, are usually held close to one another and tightly together. Imagine a bunch of folks all stuck to one another with glue. Each person can wiggle and jiggle but they can’t really move anywhere.

Atoms in a solid are the same way. Each atom can wiggle and jiggle but they are stuck together. In science, we say that the molecules have strong bonds between them. Bonds are a way of describing how atoms and molecules are stuck together.

There’s nothing physical that actually holds them together (like a tiny rope or something). Like the Earth and Moon are stuck together by gravity forces, atoms and molecules are held together by nuclear and electromagnetic forces. Since the atoms and molecules come so close together they will often form crystals.

Try this experiment and then we will talk more about this:
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Here’s what you need:

50 pennies
ruler

Download worksheet and exercises

Lay about 20-50 pennies on the table so that they are all sitting flat on the table. Now, use the ruler (or your hand) to push the pennies toward one another so that you have one big glob of pennies on the table all touching one another. Don’t push so hard that they pile on top of one another. Just get one nice big flat blob of pennies.

Pretty simple huh? However, take a look at the pennies, do you notice anything? You may notice that the pennies form patterns. How could that happen? You just shoved them together you didn’t lay them out in any order. Taa daa! That’s what often happens when solids form.

The molecules are pulled so close to one another that they will form patterns, also known as matrices. These patterns are very dependent on the shape of the molecule so different molecules have a tendency to form different shaped crystals. Salt has a tendency to be “cubey”. Go take a look… and you’ll find that they are like little blocks!

Water has a tendency to from triangle or hexagon shapes which is why snowflakes have six sides. Your pennies also form a hexagon shape. Solids don’t always form crystals but they are more common than you might think. A solid that’s not in a crystalline form is called amorphous. Before you put your pennies away I want you to notice one more thing.

Here’s what you do:

1. Take your pennies and lay them flat on the table.

2. Push them together so they all touch without overlapping.

3. Place your ruler on the right hand side of your penny blob so that it’s touching the bottom half of your pennies.

4. Slowly push the ruler to the left and watch the pennies.

You may have noticed that the penny “crystal” split in quite a straight line. This is called cleavage. Since crystals form patterns the way they do they will tend to break in pretty much the same way you saw your pennies break.

Break an ice cube and take a look. You may see many straight sections. This is because the ice molecules “cleave” according to how they formed. The reason you can write with a pencil is due to this concept. The pencil is formed of graphite crystal. The graphite crystal cleaves fairly easily and allows you to write down your amazing physics discoveries!

(The image here is a graphite crystal.) [/am4show]

Laundry Soap Crystals

Friday October 2, 2009

Can we really make crystals out of soap? You bet! These crystals grow really fast, provided your solution is properly saturated. In only 12 hours, you should have sizable crystals sprouting up.

You can do this experiment with either skewers, string, or pipe cleaners. The advantage of using pipe cleaners is that you can twist the pipe cleaners together into interesting shapes, such as a snowflake or other design. (Make sure the shape fits inside your jar.)

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Here’s what you need:

pipe cleaners (or string or skewer)
cleaned out pickle, jam, or mayo jar
water
borax (AKA sodium tetraborate)
adult help, stove, pan, and stirring spoon

Here’s what you do:

1. Cut a length of string and tie it to your pipe cleaner shape; tie the other end around a pencil or wooden skewer. You want the shape suspended in the jar, not touching the bottom or sides.

2. Bring enough water to fill the jar (at least 2 cups) to a boil on the stove (food coloring is fun, but entirely optional).

3. Add 1 cup of borax (aka sodium tetraborate or sodium borate) to the solution, stirring to dissolve. If there are no bits settling to the bottom, add another spoonful and stir until you cannot dissolve any more borax into the solution. When you see bits of borax at the bottom, you’re ready. (You’ll be adding in a lot of borax, which is why we asked you to get a full box). You have made a supersaturated solution. Make sure your solution is saturated, or your crystals will not grow.

4. Wait until your solution has cooled to about 130^oF (hot to the touch, but not so hot that you yank your hand away). Pour this solution (just the liquid, not the solid bits) into the jar with the shape. Put the jar in a place where the crystals can grow undisturbed overnight, or even for a few days. Warmer locations (such as upstairs or on top shelves) is best.

Download worksheet and exercises

DO NOT EAT!!! Keep these crystals out of reach of small kids, as they look a lot like the Rock Candy Crystals.

Here are photos from kids ages 2, 7, 9 that made their own! Great job to the Fluker Family!!

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Salt & Vinegar Crystals

Friday October 2, 2009

We’re going to take two everyday materials, salt and vinegar, and use them to grow crystals by creating a solution and allowing the liquids to evaporate. These crystals can be dyed with food coloring, so you can grow yourself a rainbow of small crystals overnight.

The first thing you need to do is gather your materials. You will need:

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Here’s what you need:

1 cup of warm water
1/4 cup salt (non-iodized works better)
2 teaspoons to 2 tablespoons of vinegar (you decide how much you want to use)
a shallow dish (like a pie plate)
a porous material to grow your crystals on (like a sponge)

First, mix together the salt, vinegar, and water in a cup. (You cal alternatively boil the water on the stove and stir in as much salt as the water will dissolve.) Add the vinegar after you turn off the heat. Next, place your sponge in a bowl and pour the solution over the sponge, submerging the sponge in the solution. Leave out, undisturbed, until the liquids evaporate, leaving behind a sheet of crystals.

Download worksheet and exercises

You can add more liquid carefully to the bowl to continue the growth of your crystals for long after the first solution dries up. Also, as your crystals grow, dot the sponge with drops of food coloring to crow various colors of crystals.

Although it takes awhile for the crystals to start growing, once they do, they will continue to grow quickly!

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Eggshell Crystals

Friday October 2, 2009

Geodes are formed from gas bubbles in flowing lava. Up close, a geode is a crystallized mineral deposit that is usually very dull and ordinary-looking on the outside. When you crack open a geode, however, it’s like being inside a crystal cave. We’ll use an eggshell to simulate a gas bubble in flowing lava.

We’re going to dissolve alum in water and place the solution into an eggshell. In real life, minerals are dissolved in groundwater and placed in a gas bubble pocket. In both cases, you will be left with a geode.

Note: These crystals are not for eating, just for looking.

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Here’s what you need:

clean egg shells
alum (check the spice section of the grocery store)
food dye
water

Download worksheet and exercises

This is a continuation of the Laundry Soap and Rock Candy experiments, so make sure you’ve done those before trying this one.

Find a clean half eggshell. Fill a small cup with warm water and dissolve as much alum in the water as you can to make a saturated solution (meaning that if you add any more alum, it will fall to the bottom and not dissolve).

Fill the eggshells with the solution and set aside. Observe as the solution evaporates over the next few days. When the solution has completely evaporated, you will have a homemade geode. If no crystals formed, then you had too much water and not enough alum in your solution.

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Salt Stalactites

Friday October 2, 2009

This is a continuation of the Laundry Soap and Rock Candy experiments, so make sure you’ve done those before trying this one.

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Here’s what you need:

two clean glass jars
yarn or string
epsom salts
water
tin foil or cook sheet
adult help, sauce pot, and a stove.

Make a supersaturated saturated solution from warm water and Epsom salts (magnesium sulfate). (Add enough salt so that if you add more, it will not dissolve.) Fill two empty glass jars with the salt solution. Space the jars a foot apart on a layer of foil or on a cookie sheet. Suspend a piece of yarn or string from one jar to the other. Wait impatiently for about three days. A stalactite should form from the middle of the string!

Download worksheet and exercises

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Water Glass & Metal Crystals

Friday October 2, 2009

This experiment is for advanced students. Water Glass is another name for Sodium Silicate (Na₂SiO₃), which is one of the chemicals used to grow underwater rock crystal gardens. Metal refers to the metal salt seed crystal you will use to start your crystals growing. You can use any of the following metals listed. Note however, that certain metals will give you different colors of crystals.

Your crystals begin growing the instant you toss in the seed crystals. These crystals are especially delicate and fragile – just sloshing the liquid around is enough to break the crystal spikes, so place your solution in a safe location before adding your seed crystals.

After your garden has finished growing to the height and width you want, simply pour out the sodium silicate solution and replace with fresh water (or no water at all). Due do the nature of these chemicals, keep out of reach of small children, and build your garden with adult supervision.

Here’s what you need to get:

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Clean glass jar
Sodium silicate (check shopping list for online ordering)
One (or more) of the following for different colors:
- White – calcium chloride (found on the laundry aisle of some stores)
- Purple – manganese (II) chloride
- Blue – copper (II) sulfate (common chemistry lab chemical, also used for aquaria and as an algicide for pools)
- Red – cobalt (II) chloride
- Orange – iron (III) chloride

Download worksheet and exercises

The seed crystals are metal salts that react with the water/sodium silicate solution to climb upwards in the solution, as the products are less dense than the surrounding solution.

Troubleshooting: If you add too many seed crystals, your solution will turn cloudy and you’ll need to start all over again! Add your seed crystals sparingly – you can always add more later.

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Charcoal Crystals

Friday October 2, 2009

Charcoal crystals uses evaporation to grow the crystals, which will continue to grow for weeks afterward. You’ll need a piece of very porous material, such as a charcoal briquette, sponge, or similar object to absorb the solution and grow your crystals as the liquid evaporates. These crystals are NOT for eating, so be sure to keep your growing garden away from young children and pets! This project is exclusively for advanced students, as it more involves toxic chemicals than just salt and sugar.

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The materials you will need for this project:

Charcoal Briquettes (or pieces of sponge or brick or porous rock)
Distilled Water
Uniodized Salt
Ammonia (Keep this out of reach of children!)
Laundry Bluing
Food Coloring (optional)
Pie Plate (glass or tin)
Measuring Spoons
Disposable Cup
Popsicle Stick

Download worksheet and exercises

The first thing you’ll need to whip up a batch of solution, then you’ll start growing your garden. Here’s how you do it:

1. Into a disposable cup, stir together (use a popsicle stick to mix it up, not your good silverware) 1 cup of water, 1 tablespoon of ammonia, 1/2 cup of laundry bluing, and 1/2 cup of salt (non-iodized).

2. Place your charcoal or sponge in a pie tin and pour your solution from step 1 over it.

3. Wait impatiently for a few days to one week. As the liquid evaporates, the salts are left behind, forming your crystals.

4. Continue to add more solution (to replace the evaporated solution) to keep your crystals growing. Think of it as ‘watering’ (with your special solution) your crystals, which are growing in your ‘soil’ (sponge).

5. You can dot the sponge with drops of food coloring to grow different colors in your garden.

Questions to Consider…

Why do you think you needed ammonia and ‘laundry bluing’ for this experiment? What is ‘laundry bluing’, anyway? Why do the crystals form just on the porous object and not the glass/metal pie plate? Let us know in the comment field below what you think:

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Volcanoes

Sunday November 2, 2008

If you’ve ever wanted to make your own version of a volcano that burps and spit all over the place, then this is the experiment for you. We used to teach kids how to make genuine Fire & Flame volcanoes, but parents weren’t too happy about the shower of sparks that hit the ceiling and fireballs that shot out of the thing… so we’ve toned it down a bit to focus more on the lava flow.

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FIRST STEP: Make the volcano.

The first thing to do is mix up your own volcano dough. You can choose from the following two mixtures. The Standard Volcano Dough is akin to play dough; the Earthy Volcano Dough looks more like the real thing. Either way, you’ll need a few days on the shelf or a half-hour in a low-temperature oven to bake it dry. Alternatively, you can use a slab of clay for the dough.

Standard Volcano Dough Mix together 6 cups flour, 2 cups salt, ½ cup vegetable oil, and 2 cups warm water. The resulting mixture should be firm but smooth. Stand a water or soda bottle in a roasting pan and mold the dough around it into a volcano shape.
Earthy Volcano Dough Mix 2½ cups flour, 2½ cups dirt, 1 cup sand, and 1½ cups salt. Add water by the cup until the mixture sticks together. Build the volcano around an empty water bottle on a disposable turkey-style roasting pan. It will dry in two days if you have the time, but why wait? You can erupt when wet if the mixture is stiff enough! (And if it’s not, add more flour until it is.)

SECOND STEP: Create the reaction.

Soda Volcanoes Fill the bottle most of the way with warm water and a bit of red food coloring. Add a splash of liquid soap and ¼ cup baking soda. Stir gently. When ready, add vinegar in a steady stream and watch that lava flow.

Air Pressure Sulfur Volcanoes Wrap the volcano dough around an 18” piece of clear, flexible tubing. Shape the dough into a volcano and place in a disposable roasting pan. Push and pull the tube from the bottom until the other end of the tube is just below the volcano tip. If you clog the ends of the tubing with clay, just trim away the clog with scissors. Using your fingers, shape the inside top of the volcano to resemble a small paper cup. Your solution needs a chamber to mix and grow in before overflowing down the mountain. The tube goes at the bottom of the clay-cup space. Be sure the volcano is SEALED to the cookie sheet at the bottom. You won’t want the solution running out of the bottom of the volcano instead of popping out the top!

- Make your chemical reactants.
  - Solution 1: Fill one bucket halfway with warm water and add 1 to 2 cups baking soda. Add 1 cup of liquid dish soap and stir very gently so you don’t make too many bubbles.

- - Solution 2: Fill a second bucket halfway with water and add 1 cup of aluminum sulfate (also called alum; find this in the gardening section of the hardware store or check the spice section of the grocery store). Add red food coloring and stir.

- - Putting it all together: Count ONE (and pour in Solution 1) … TWO (inhale air only!) …… and THREE (pour in Solution 2 as you put your lips to the tube from the bottom of the volcano and puff as hard as you can!) Lava should not only flow but burp and spit all over the place!

Download Student Worksheet & Exercises

Exercises

How is this activity similar to the volcanoes on Mars?
What gas is produced with this reaction?
Which planets have volcanoes?

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