I like rocks so much that I used to try to eat them. Rocks are high in minerals, but they hurt my teeth. So I learned how to make edible rocks out of pure sugar. I eat several for dessert after every meal. (My teeth remain strong and white because I brush them frequently.) When Professor Zoober saw my gemlike crystal rock candy, he was very pleased. “We can trade the candy rocks for robot parts and other supplies!” he said. After that, we didn’t need to pay for anything with money: We barter for everything we need with the candy rocks. Why don’t you try making some tasty sugar rocks and see if you can buy some toys with them? That is, if you don’t eat them all yourself!
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SAFETY KID SAYS: “Since this experiment requires boiling water, make sure a grown-up is around to help!” |
Materials
Paper clip
Thin string
Pencil
Clean, empty jam or peanut butter jar
1 cup distilled water. Note: It’s important to use distilled water, since if you use tap water, the crystals might not have
Tools
Tape or rubber band
Plate
Saucepan
Measuring cups and spoons
Metal or plastic spoon (for stirring)
Aluminum foil (optional)
Paper
1 Tie the paper clip to one end of the string and tie the pencil to the other end of the string. Lay the pencil flat against the rim of the jar. The paper clip should hang in the center of the jar, just ¼ inch above the bottom of the jar. Adjust the length of the string by rolling it on the pencil, then secure the string by taping it to the pencil or wrapping the pencil with a rubber band.
2 Take the pencil/clip/string out of the jar. Dip the string in distilled water, then sprinkle some sugar on it. Set it on a plate.
3 Boil the distilled water and remove it from the heat.
4 Slowly add the sugar, a tablespoon at a time, to the water and stir it carefully. You might have to heat the water on the stove some more to make the mixture clear, so there are no more sugar granules.
5 When the solution cools down a bit, pour it into the clean jar. Put the lid on it, or if you don’t have the lid, use foil to cover the top. Let it set overnight.
6 The next day, take the lid off and lower the string into the jar of sugar water. Rest the pencil on the rim of the jar, so the string hangs.
7 Keep the jar where it won’t be disturbed for several days. Cover the top with a piece of paper.
8 After three days, inspect the jar. Small crystals should have appeared on the string. If not, wait a few more days. If they still haven’t appeared, start over, making sure everything is very clean. If crystals have formed, watch them grow, day by day.
9 The crystals will eventually stop growing. If you want them to get bigger, pour the sugar solution into a saucepan, heat it up, and dissolve more sugar into it. You might need to add a little water, since some of it gets lost due to evaporation.
HOW IT WORKS: At room temperature, a certain amount of water is able to dissolve a certain amount of sugar, and no more. When a jar of water contains as much dissolved sugar as it can possible hold, it is said to be fully saturated. If you heat the water up, it’s able to dissolve more sugar. When you cool that water down to room temperature, the sugar stays dissolved in the water; this is called a super-saturated solution. The extra dissolved sugar is “looking” for a way to fall out of the solution, and when it finds a seed crystal (the sugar you sprinkled on the string), it attaches to that, making the seed grow larger and larger as more sugar leaves the solution.
