Chemistry Primer

Rock Candy Experiment

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Make Your Own Rock Candy

  • 1 cup water
  • 3 cups table sugar (sucrose)
  • clean glass jar
  • pencil
  • string (not nylon)
  • pan for boiling water and making solution
  • stirring rod or spoon

Boil the water, and be careful not to splash yourself and don't touch the pan because it's hot! Stir in the sugar, a teaspoonful at a time. Keep adding sugar until it starts to accumulate at the bottom of the pan and no matter how much you stir it won't dissolve anymore. You have just made simple syrup, and your sugar solution is saturated. The more saturated your solution, the faster your crystals will grow! If you want colored crystals, add a few drops of your favorite colored food coloring. Pour your solution into the glass jar without getting any of that undissolved sugar in the jar. Dip your string into the solution and dip it in sugar. This will start a seed crystal which makes sure your candy grows on the string and not on the bottom of the glass jar! Tie the string to your pencil or butter knife. Make sure the string is made of cotton, wool, or yarn. Crystals will grow on these but not on nylon. Set the pencil across the glass jar, making sure the string isn't touching the sides or the bottom but is dangling into the liquid. Place the jar somewhere where it won't get knocked over. After a day you should be able to see your crystals growing. Let the crystals grow until they are as big as you'd like or have stopped growing. Now you can pull out the string and allow the crystals to dry on a paper towel. Now you have rock candy or a pretty decoration!

Tips - To add flavoring to your rock candy, you can sprinkle in some cinnamon, or squeeze the juice from a lemon, lime, or an orange.

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