Sugar Crystals/ Rock Candy


We did this with a group of friends so we started with 18 cups of sugar but ended up using a whole 25 pound bag to get the solution supersaturated.


We used superfine sugar which dissolved really quickly so it was hard to tell when there were bits still on the bottom. We also flavored it with some LifeSaver candies.


We used 4 different jars to grow our crystals. In one we had a string suspended in it with no lid. In the second, we used a skewer with a lid on. In the third, we had a skewer with the lid partway off. And in the fourth, we had a skewer and the lid was mostly off. The only major difference we noticed was with the jar with the string and no cover at all. the crystals are not lined up as neatly and it’s kind of big and chunky. The skewers helped to form the crystals more uniformly. We also don’t think evaporation was too important in the forming of the crystals.


We learned that sugar crystals are shaped like prisms and rectangles and that the growth is not just a multiplication of more crystals, the crystals themselves actually get bigger. Most of our growth happened within the first 3 weeks. They haven’t changed much since then. So we concluded that this had something to do with the superfine sugar versus regular sugar. Next time we’ll have to try it with regular to compare the growth rate.


This was fun to do and hopefully our mom will actually let us eat it now!


Click on an image to enlarge.


Have a question ?

Tell us what you're thinking...

Comments

10 Responses to “Rocks we can eat!”

  1. I love research, and I appreciated the comparisons.

  2. Everyone else has already made some good comments. I can only add that trying it with the different variables is good for teaching about quality control and ways to improve a product.

  3. Constance says:

    Interesting difference between the string and scewer rock candy. Thanks!

  4. Those large sugar crystals are pretty. Like they could be a gift.
    Hm-m-m-m! Maybe you could make Christmas gifts with a little food coloring.
    I bet it took patience to wait for the crystals to form.

  5. Elizabeth says:

    MMMMMMM…..Tasty! Your friends would want some too! My sister always love to do this as a kid! How fun to watch the sugar grow! Did they taste good?? I hope you remembered to brush your teeth. I loved that you did 4 different jars…..the variables are really interesting!

  6. Oh, this reminds me of trips to Cripple Creek, CO when I was little. Getting rock candy was the highlight of the visit. I had no idea you could actually make it at home yourself. I would have SO done that when I was kid.

  7. This sounds like a lot of fun and they are pretty, too.

  8. Lindsay Kellock says:

    Wish I had some …

  9. Who knew science could taste good! Yes, you can eat them now.

  10. Ummmmmmmmmmm save me some .What a clever idea.Mary Moore