When it is exposed to air, the iron begins to rust. This rusting process produces heat. The second contains a solution of the chemical sodium acetate and a small metal disc. When the disc is bent, ...

A seed crystal can be dropped into a saturated solution of sodium acetate. The solution will suddenly crystallize and turn to solid. Alternately, the solution may be slowly poured out onto a seed ...

Commercial heat packs (containing iron and water, or supersaturated sodium acetate) and cold packs (various ammonium salts) can be used to show exo- and endothermicity. Heat packs that contain iron ...