Sodium acetate trihydrate, chemical formula NaC2H3O2‧3H2O, is readily formed by the reaction of acetic acid (vinegar) and sodium hydroxide, sodium carbonate or sodium bicarbonate.

Medical Use: Sodium acetate is used in medicine to replenish electrolytes. It also serves as a diuretic. A most interesting application of sodium acetate is in reusable heating pads. Sodium acetate trihydrate contains three waters of crystallization. Heat it up to 58 degrees centigrade, and those waters are released by the crystals. They dissolve the no longer hydrated sodium acetate, replacing the solid with a solution. This solution can then be cooled without re-crystallization, to room temperature. When desired, and with the proper stimulus, this liquid can be forced to crystallize again. The act of crystallization releases heat to the body parts the user desires.

Industrial Uses: Sodium acetate is an alkaline salt, being the product of a strong base and a weak acid. Thus, its alkalinity, as well as its low price, makes it attractive in the neutralization of industrial mineral acids discharge.
In pest control, sodium acetate is under study for use as a component of nematicides. Nematodes may be drawn to sodium acetate as a kind of bait, even as pheromones can be used to draw certain insects.