A) A supersaturated solution of sodium acetate is crystallized by pouring it onto a seed crystal, forming a stalagmite-like solid. Heat is radiated from solid.

B) A crystal is dropped into a test tube, forming thin monoclinic crystals. This may be illuminated from below; heat is radiated from the solid.

This demonstration is also available on video and JCE Software “Chemistry Comes Alive!” Vol. 2 CD-Rom.

Source: Shakhashiri, B.Z. Chemical Demonstrations: A Handbook for Teachers of Chemistry

Year: 1983 Vol: 1 Page: 27

Keywords: Crystallization, Sodium acetate, Exothermic, Solutions, Supersaturated

Ratings:

Hazard: Some

Use of mildly reactive chemicals
Electric shock hazard

Effectiveness: Good

Results are clearly observable without guidance
Time to results is low
Good connection from demo to course material
Moderate reliability

Difficulty: Medium

Some intermediate steps to results
Careful manipulations are required
Reactions at non-standard conditions
Demos in which a display is used

Safety Precautions:

Eye protection is required
Gloves are required
Use chemically inert surface
Use UL approved three-prong plug and outlet

Class: Intermolecular Forces, Chemical Equilibrium, Thermodynamics, Liquids and Solids, Phase Changes

Division: General

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