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Make Rock Candy

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Rock Candy is one of the many popular sweet treats you can enjoy at Sauder Village! Making Rock Candy at home is a delicious way to learn about the science principle of how crystals form! Rock candy projects take about 10 days from start to finish. What a delicious science experiment!

Explanation - Crystals can form in two ways - precipitation or evaporation. Super-saturated sugar solutions contain more sugar than liquid. As the solution cools, the sugar forms on the string and precipitates, attaching to the string. Evaporation occurs over time as water leaves the solution. In this method the rock candy crystals grow molecule by molecule. After the crystals have grown for a week there will be about a quadrillion crystal molecules attached to the string.

Experiment - For each rock candy specimen you will need two cups of boiling water and four cups of sugar. While on medium heat, stir in the sugar until it has completely dissolved and returned to a rolling boil. Remove the saucepan from the heat and pour the sugar mixture into a glass jar. Cut a piece of cotton string about the size of the glass jar; tie a washer to one end and a pencil to the other end. Dip the string into the sugar mixture until fully saturated; set aside on a piece of wax paper for a few days. Cover the jar with a piece of wax paper.

Place the dried string into the sugar mixture, washer side down, the pencil lying across the top of the jar. Within the first few days you should notice crystals forming on the string. Set the jar aside for about a week or until the rock candy is your desired size.

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Fun Facts - Crystals grow more quickly in places where a crystal has already formed. As the water evaporates from the dipped string, small sugar crystals, also known as "seed crystals" are left behind on the string. The seed crystals encourage the growth of more crystals, and will continue growing until the string is removed from the sugar solution and rinsed with water.



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