Phosphoric acid or phosphate, chemical formula H3PO4, molecular weight of 97.9724, is a kind of common inorganic acid, is in strong acid. By dissolving in hot water can be obtained phosphorus pentoxide. The use of sulfuric acid for the treatment of apatite. Phosphoric acid easily deliquescent in the air. Heating will dehydrate to get pyrophosphate, and then further dehydration to get partial phosphoric acid. Phosphoric acid is mainly used in pharmaceutical, food, fertilizer and other industries.