Special Science Teleclass: Thermodynamics

Monday December 1, 2014

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, too!


You’ll discover how to boil water at room temperature, heat up ice to freeze it, make a fire water balloon, and build a real working steam boat as you learn about heat energy. You’ll also learn about thermal energy, heat capacity, and the laws of thermodynamics.


Materials:


  • cup of ice water
  • cup of room temperature water
  • cup of hot water (not scalding or boiling!)
  • tea light candle and lighter (with adult help)
  • balloon (not inflated)
  • syringe (without the needle)
  • block of foam
  • copper tubing (¼” diameter and 12” long)
  • bathtub or sink
  • scissors or razor
  • fat marker (to be used to wrap things around, not for writing)
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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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Balloon Gymnastics

Sunday September 5, 2010

Is it warmer upstairs or downstairs? If you’re thinking warm air rises, then it’s got to be upstairs, right? If you’ve ever stood on a ladder inside your house and compared it to the temperature under the table, you’ve probably felt a difference.


So why is it cold on the mountain and warm in the valley? Leave it to a science teacher to throw in a wrench just when you think you’ve got it figured out. Let’s take a look at whether hot air or cold air takes up more space. Here’s what you do:


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Homemade Thermostat

Sunday September 5, 2010

If you can remember thermostats before they went ‘digital’, then you may know about bi-metallic strips – a piece of material made from of two strips of different metals which expand at different rates as they are heated (usually steel and copper). The result is that the flat strip bends one way if heated, and in the opposite direction if cooled.


Normally, it takes serious skill and a red-hot torch to stick two different metals together, but here’s a homemade version of this concept that your kids can make using your freezer.  Here what you do:


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Ghost Coin

Sunday September 5, 2010

This spooky idea takes almost no time, requires a dime and a bottle, and has the potential for creating quite a stir in your next magic show.  The idea is basically this: when you place a coin on a bottle, it starts dancing around. But there’s more to this trick than meets the scientist’s eye.


Here’s how you do it:


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Food Dye Currents

Sunday September 5, 2010

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!


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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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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Boiling Room Temperature Water

Sunday September 5, 2010

The triple point is where a molecule can be in all three states of matter at the exact same time, all in equilibrium. Imagine having a glass of liquid water happily together with both ice cubes and steam bubbles inside, forever! The ice would never melt, the liquid water would remain the same temperature, and the steam would bubble up. In order to do this, you have to get the pressure and temperature just right, and it’s different for every molecule.


The triple point of mercury happens at -38oF and 0.000000029 psi. For carbon dioxide, it’s 75psi and -70oF. So this isn’t something you can do with a modified bike pump and a refrigerator.


However, the triple point of water is 32oF and 0.089psi. The only place we’ve found this happening naturally (without any lab equipment) is on the surface of Mars.


Because of these numbers, we can get water to boil here on Earth while it stays at room temperature by changing the pressure using everyday materials. (If you have a vacuum pump, you can have the water boil at the freezing point of 32oF.)


Here’s what you need to do:


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Stairstep Candles

Sunday September 5, 2010

Fire is a chemical reaction (combustion) involving hot gases and plasma. The three things you need for a flame are oxygen, fuel, and a spark. When the fuel (gaseous wax) and oxygen (from the air) combine in a flame, one of the gases produced is carbon dioxide.


Most people think of carbon dioxide as dry ice, and are fascinated to watch the solid chunk sublimate from solid straight to gas, skipping the liquid state altogether. You’ve seen the curls of dry ice vapor curl down and cover the floor in a thick, wispy fog. Is carbon dioxide always more dense than air, or can we get it to float?


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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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Football Ice Cream

Wednesday June 30, 2010

Is it hot where you live in the summer? What if I gave you a recipe for making ice cream that doesn’t require an expensive ice cream maker, hours of churning, and can be made to any flavor you can dream up? (Even dairy-free if needed?)


If you’ve got a backyard full of busy kids that seem to constantly be in motion, then this is the project for you.  The best part is, you don’t have to do any of the churning work… the kids will handle it all for you!


This experiment is simple to set up (it only requires a trip to the grocery store), quick to implement, and all you need to do guard the back door armed with a hose to douse the kids before they tramp back into the house afterward.


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