Super Saturation
Teacher Notes
COS Objectives:
Standard 4: Solubility
Standard 4: Bullet 1: Solubility Curves
Standard 4: Bullet 4: Rate of solution
ENGAGE (recommended for Effect of Temperature on Solubility of a Salt
Demonstration of rapid precipitation from a Reusable Hand Warmer
(1) Explain the concepts of saturation, supersaturation, crystallization, and seed crystals
(2) Hand each pair of students one of the Reusable Hand Warmers.
(3) Have one student Flex the metal disc back and forth until crystals start to form. Once crystals
start to farm gently knead the pouch to intensify the heat.
Materials for Engagement activity
Reusable Hand Warmer
Large Beaker
Hot Plate
Water
Tongs
Restoring to liquid form (using a hotplate)
(1) In a large beaker boil water.
(2) Hold the Reusable Hand Warmer with the Tongs in the boiling water (be sure to not let it touch
the bottom of the beaker or the plastic will melt!
If you get tired of holding the Reusable Hand Warmer with the Tongs, an alternative is to wrap it
in a heavy cloth towel. The cloth towel should protect the plastic from melting against the
bottom of the beaker. Then you can let the protected (cloth wrapped) Reusable Hand Warmer
drop to the bottom of the beaker.
(3) Remove the Reusable Hand Warmer when ALL of the crystals are gone (approx. 7-10 minutes)
(4) Let it cool before use (the plastic is wearer when hot and the metal disc may slice it open).
NOTE: If you want to use a microwave to Restore the Hand Warmer watch the video at:
http://beprepared.com/article.asp?ai=725&