How do hand warmers work?


Both air-activated hand warmers and supersaturated solution hand warmers work by producing an exothermic reaction. Both types work best when kept covered rather than exposed to the cold.

Air-activated hand warmers contain iron, vermiculite, carbon, salt and cellulose. When air hits the iron, the process of oxidation begins, with the creation of rust releasing heat. The other chemicals help disperse the heat evenly. Air-activated hand warmers are safe for use on airplanes and are typically disposable. Supersaturated solution hand warmers contain water, salt and a metal disc. When the user snaps the disc, the crystals of the metal precipitate, creating warmth. Supersaturated solution hand warmers are reusable if they are boiled and allowed to cool.

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Gel hand warmers work by storing sodium acetate in a liquid state, and then allowing it to rapidly crystallize. Because sodium acetate has a freezing point of ...
Sodium Acetate (C2H3NaO2) is a white powder often used in hand warmers. First, the hand warmer is heated to above 100 degrees Celsius and allowed to cool to room ...
Hand warmers are small disposable packets that are held in the hand and produce heat on demand to warm cold hands. Packaged hand warmers contain iron particles ...
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