Make Your Own Rock Candy
Have fun making rock candy with your kids. It's a delicious treat which doubles as a really cool science experiment! The entire process can take up to a week, but it's well worth it as your kids watch the sugar crystals growing over time.
- Large glass jars (Mason jars work well) - 1 per flavour
Ingredients (per stick):
- 1 cup water
- 3 cups granulated sugar
- 1/2 to 1 tsp. flavouring extract or oil (optional)
- Food colouring (optional)
Note: If making multiple rock candy sticks, you will have to repeat this recipe for each skewer. Change the colour and flavourings for each. The ratio should always be close to 3:1.
- Place the water in a medium-sized pot and bring it to a boil. Begin adding the sugar, one cup at a time, stirring after each addition. You will notice that it will take longer for the sugar to dissolve after each addition. Continue to stir and boil the syrup until all of the sugar has been added and it is all dissolved. Remove the pan from the heat.
- If you are using colours or flavourings, add them now. For extracts, add 1 tsp. of extract. If are using flavouring oils, only add 1/2 tsp. and make sure you don’t stand right in front of of the pan, the scent can be very strong as it rises in the steam. Add 2 to 3 drops of food colouring and stir to ensure even, smooth colour.
- Allow the sugar syrup to cool for approximately 10 minutes, then pour it into the prepared jar.
- Prepare your skewer. Wet the skewer and roll it in sugar. Let dry COMPLETELY. The rock candy needs the sugar to grow on. If the sugar on the sticks isn't dry, it will immediately dissolve in the water. When dry, attach a clothespin at the top of the skewer.
- Lower the sugared string or skewer until it hangs about 1 inch from the bottom. The clothespin should stop the skewer from falling into the jar. Make sure that the sticks are not touching the bottom or the sides of the jar.
- Place your jar in a cool place, away from harsh lights, where it can sit undisturbed. Cover the top loosely with plastic wrap or paper towel.
- You should start to see sugar crystals forming within 2 to 4 hours.
Allow the rock candy to grow until it is the size you want however 1 week should be sufficient. Remove the candy sticks from the jar and place it on a plate to dry. Once dry you will have a yummy treat to enjoy! Wrap them in clear cellophane or treat bags as gifts.
The Science Behind the Candy:
Review the scientific facts in this experiment with your kids! You created a 'supersaturated solution' by heating a saturated sugar solution (a solution in which no more sugar can dissolve at a particular temperature), then allowing it to cool. A supersaturated solution is unstable; it contains more solute (sugar) than can stay in a liquid form. The sugar will come out of the solution, forming what's called a 'precipitate.' As time passes, the water will slowly evaporate from the solution. As it does, the solution becomes more saturated and sugar molecules will continue to come out of the solution and collect on the seed crystals on the skewer. The rock candy crystals grow molecule by molecule. Your finished rock candy will be made up of about a quadrillion (1,000,000,000,000,000) molecules attached to the stick!