Soluble in water and alcohol. It is slowly oxidized into phosphoric acid in the air and decomposed into phosphoric acid and phosphine (highly toxic and explosive) when heated to 180 ºC. Phosphite is a dibasic acid, which is slightly more acidic than phosphoric acid. It has strong reducibility. It is easy to reduce silver ion (Ag +) to metal silver (Ag), and can reduce sulfuric acid to sulfur dioxide. It has strong hygroscopicity, deliquescence and corrosiveness. Phosphite is mainly used as reducing agent, nylon whitening agent, phosphite raw material, pesticide intermediate and organic phosphorus water treatment agent.