Homemade Rock Candy

Rock candy is a fun and edible way for kids to learn about chemistry, specifically the process of crystallization where sugar molecules, when cooled, form a solid structure. The children will love watching the crystals form for 6 to 7 days making rock candy. The recipe from wearenotmartha.com is below. 

Saturated Solution:
When you dissolve a large amount of sugar in water, you create a saturated solution, meaning the water holds as much sugar as it can at a given temperature. 

Supersaturation:
Heating the water further allows you to dissolve even more sugar, creating a supersaturated solution, which is unstable and prone to crystallization. 

Crystallization:
As the solution cools, the sugar molecules start to come out of the solution and form a solid, crystalline structure.

Seed Crystals:
The sugar-coated string or stick acts as a seed crystal, providing a surface for the sugar molecules to attach and grow, forming the rock candy crystals. 

Nucleation:
The initial process of molecules sticking together to form a crystal is called nucleation. 

Molecular Attraction:
Sugar molecules are attracted to each other, and this attraction is what causes them to form crystals. 

Temperature:
As the temperature decreases, the sugar molecules have less energy to stay dissolved, so they come out of solution and form crystals. 

Evaporation:
As the water evaporates, the sugar concentration increases, further promoting crystallization. 

You Will Need:

Recipe from wearenotmartha.com
Photo by Stephanie Felzenberg

5 Wooden Skewers or Cake Pop Sticks
16 oz Mason Jars
5 Clothespins or Chip Clips
4 Cups Water
10 Cups Granulated Sugar Plus More for Coating Skewers

What to Do:

1. Dip one end of the skewer or cake pop stick into water and roll in white sugar. Make the sugar layer 2 to 4 inches thick. Submerge skewers in water, coat them in sugar, and then set out to dry for 1 to 24 hours. This is your crystal seed. 

2. Make sure your jars are clean and not cold (run hot water through them if necessary). Attach a clothespin or chip clip to the top of each skewer and then balance over the top of jars. Be sure your skewer is hanging about an inch from the bottom of the jar as the rock candy crystals will stick to the bottom of the jar and will make it tough to remove skewers.

3. In a large saucepan, bring water to a boil. Add sugar in one cup at a time, stirring with a wooden spoon and letting each cup fully dissolve before adding the next. You’ll notice it becomes harder and harder for the sugar to dissolve as you add more in.

4. Once your final cup of sugar has been dissolved, let mixture simmer for about 5 minutes before removing from heat. Let mixture rest off the heat for about 15 minutes.

5. Divide sugar solution amongst the 5 prepared jars. I recommend bringing your jars to where they’ll be resting for the next 6-7 days at this time. Be sure to use caution as the jars will be very hot. Once they’re in their resting spots, place prepared skewers into solution. You’ll want to try your best not to move jars around much once skewers are in place.

6. You’ll likely see little crystals forming within hours, but you’ll want to let the jars rest for 6-7 days to let sugar crystals fully form.

7. When ready to remove rock candy sticks from jars, use your finger or a fork to gently crack the hardened sugar on top of the jar and gently wiggle the stick to release. Let solution drizzle from stick (I recommend setting the candy over an empty jar or bowl to let it drip) before enjoying the candy.

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References:

Recipe from wearenotmartha.com
Photo by Stephanie Felzenberg