supersaturated
The temperature dependence of solubility can be exploited to prepare supersaturated solutions of certain compounds. A solution may be saturated with the compound at an elevated temperature where the solute is more soluble and subsequently cooled to a lower temperature without precipitating the solute. The resultant solution contains solute at a concentration greater than its equilibrium solubility at the lower temperature i. , it is supersaturated and is relatively stable. Precipitation of the excess solute can be initiated by adding a seed crystal see the video in the Link to Learning earlier in this module or by mechanically agitating the solution. Some hand warmers, such as the one pictured in Figure 11.18, take advantage of this behavior.