Reusable Heat Pack
Description: A sodium acetate crystallization and reversible system that is commercially available. By bending the metal disc in the bag, the sodium acetate crystalizes and gives off heat. Placing the bag in boiling water redissolves the sodium acetate, and the bag may be reused.
This demonstration is also available on video and JCE Software: “Chemistry Comes Alive!” Vol. 2 CD-Rom
Source: Journal of Chemical Education
Year: 1991 Vol: 68 Page: 780
Keywords: Sodium acetate crystallization, Re-solution, Metal disc, Boiling water
Rating: 
Hazard: Low
- Chemically self-contained
Effectiveness: Average
- Results are observable with guidance
- Secondary observations
- Mild effects are seen by audience
- Time to results is low
- Good connection from demo to course material
Difficulty: Low
- Simple procedures
- Simple manipulations for most to perform
- If remote temperature indication is used, difficulty is medium
Safety Precautions:
- Eye protection required
- Use of UL approved three-prong plug and outlet
Class: Thermochemistry, Solubility
Division: General
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