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What chemical reaction makes cold packs get cold?
1 Answer
- Anonymous2 decades agoFavorite Answer
It's not a reaction, but rather the dissolution of a salt (usually ammonium nitrate) in water. When you break the inner water pack, the ammonium nitrate dissolves. This process for this particular salt is highly endothermic, that is it absorbs heat, reducing the temperature of the pack.
A reverse reaction happens w/ instant heat packs, except us the salt precipitates (solidifies), an exothermic process, giving off heat.