Phosphoric acid, also known as orthophosphoric acid, is a common inorganic acid with the chemical formula H?PO? and a molecular weight of 97.995. It is non-volatile, resistant to decomposition, and exhibits almost no oxidizing properties. It shares the general characteristics of acids and is a triprotic weak acid. Its acidity is weaker than that of sulfuric acid and nitric acid but stronger than acetic acid and boric acid. Phosphoric acid is prone to deliquescence in air and loses water upon heating to form pyrophosphoric acid; further dehydration yields metaphosphoric acid. It is primarily used in industries such as pharmaceuticals, food, and fertilizers, including applications as a rust inhibitor, food additive, in dental and orthopedic surgery, as an etchant in electronics, electrolyte, flux, dispersing agent, industrial etchant, raw material for fertilizers, and component of household cleaning products. It can also serve as a chemical reagent.