Phase changes of water - Oakland Schools

Procedure:
Hand warmers can be passed out among the audience (for smaller groups there should
be enough for each or at least every other student). Have the student click the metal
disk inside the hand warmers to activate the crystallization. They should notice that the
crystallization will begin at the metal disk and spread outward though the whole
package. As an alternative, the large flask containing the sodium acetate solution can
be used. To activate the crystallization, add a single seed crystal of sodium acetate. If
the solution has been regenerated properly you should observe a long crystalline spike
run out from the seed crystal and eventually spread through the whole solution. As the
solution crystallizes, the system will give off heat.
39