Rock Candy

Observations:

*Many crystals formed at the bottom of the jar as well as on the string

*Thick layer of crystals on the bottom of the jar

*More/thicker crystallization around the paper clip area

*Equal width/size around the string

*Higher altitude of crystals only on the right half of the jar

*Slight crust of crystallization on the top solution (along the rim of the jar)

*Solution without movement/stiff and very viscose

Discussion Questions:

1. Why does the string need to be soaked and then dried?

The string will provide the surface on which the crystals will grow. As water evaporates from the string, small crystals of sugar will appear on the string. These tiny seed crystals provide starting points for larger crystals. Future growth will be concentrated around these points.

2. How are crystals grown?

You have created a supersaturated solution by first heating a saturated sugar solution and then allowing it to cool. A supersaturated solution is unstable; it contains more solute than can stay in a liquid form, so the sugar (the solute) will come out of solution. Then evaporation occurs as time passes, the water will evaporate slowly from the solution. As the water evaporates, the solution becomes more saturated and sugar molecules will continue to come out of the solution and collect on the seed crystals on the string. The rock candy crystals grow molecule by molecule.

3. How do crystals form and how do we control its rate of growth?

The key is giving them lots of time (about 7 days) to grow. As the water (the solvent) evaporates, sugar crystals form on the string or stick, and the shapes that they form reflect the shape of individual sugar crystals. By gently suspending the prepared string into the solution and let sit at room