How do heat packs work?
Heat packs are used to treat injuries, especially those of athletes, to provide warmth and to loosen injured muscles. Chemical reactions are responsible for the heat energy produced in heat packs.Types of Heat PacksThe chemical reaction varies based on the type of heat pack being used. Disposable one-time-use heat packs can produce more heat through the reaction of water and calcium chloride or magnesium sulfate. Reusable heat packs release heat through the crystallization of sodium acetate liquid.Disposable ReactionIn a disposable heat pack, a small compartment of water is usually located deep within the heat pack already inside a solution of calcium chloride or magnesium sulfate.Reusable Pack ReactionSodium acetate has a freezing point of 130 degrees Fahrenheit, but forms a very stable liquid that can be cooled as low as room temperature before crystallization occurs. When clicked, a stainless-steel disc inside the pack provides a surface for sodium-acetate crystals to begin forming
