Hobbies And Interests
Supersaturation
Supersaturation occurs when more of a substance is added to a liquid than dissolves at room temperature. The formation of rock crystals is an example of super saturation in action. Boil two cups of water in a saucepan and add four cups of sugar. Stir the mixture until the sugar completely dissolves. Transfer the water to a jar and cover with wax paper. Tie a string to the center of a pencil and weigh down the end of the string with a small weight, such as a metal washer. Place the string in the solution for a few seconds and take it out again. Let it dry over a day or two and then place it back into the solution. The supersaturated sugar collects on the string and creates rock candy crystals.
The Chemistry of Taste
Exploring the sense of taste by experimenting with different substances is a fun way to learn. Make three batches of rock crystal candy with the first using plain sugar, the second using brown sugar and the third using maple syrup. After the crystals form, have the child sample each one and explain how and why it tastes different from the others.
Solubility
Make three batches of rock candy and add a different color food coloring to each one. When the crystals form, they take on the shade of the food coloring. Ask the child why the sugar and water solution and rock crystals turned the color of the food coloring. The food coloring is soluble in the solution, so the solution takes on the color. If it was not soluble, then it would form two separate layers like oil and water.
Crystal Shapes
Show the children the shape of individual crystals of sugar under a microscope. Take particular note of the shape and geometry of the individual crystals. Discuss why crystals take that shape. Make a batch of rock crystals and ask the children about the shapes of the large crystals. Place the rock crystals under the microscope and note how their shape is similar to sugar crystals. Talk about how the rock candy is made up of many sugar crystals, which gives it that distinct shape.