Because crystallization of these compounds is exothermic, supersaturated solutions of them act as the phase change materials, or heat reservoirs, in commercial hand warmers. For 10 points each:
[10m] Name these ionic solids that contain stoichiometric amounts of water.
ANSWER: salt hydrates
[10e] These lipids are a popular cheaper option for large-scale heat storage. The paraffin type of these materials stores the heat used in candles.
ANSWER: paraffin waxes [prompt on alkanes; prompt on aliphatic compounds]
[10h] These mixtures are preferred over both hydrates and waxes as phase-change materials for low-temperature heat storage. These mixtures occur at the triple point of a binary phase diagram when two alloys melt at the same temperature.
ANSWER: eutectic mixtures [or eutectics; reject “eutectoid” mixtures]
<Adam Silverman, Science - Chemistry> ~20761~ <Editor: Adam Silverman>