The chemical formula of phosphoric acid is H3PO4, CAS number 7664-38-2. The pure product is colorless and transparent orthorhombic crystals. The industrial grade is mostly colorless and viscous liquid, odorless and slightly sour. It is easily soluble in water and miscible with ethanol. The aqueous solution is weakly acidic. When heated to 213°C, it will lose water and form pyrophosphoric acid, and further heating will form metaphosphoric acid. It has stable chemical properties and is not easy to decompose. It is a ternary medium-strong acid that can react with alkali to form normal salts and acid salts (such as potassium dihydrogen phosphate and diammonium hydrogen phosphate). Phosphoric acid is widely used in agriculture (producing high-efficiency phosphate fertilizers such as diammonium phosphate and monoammonium phosphate), industry (metal surface phosphating treatment for rust prevention, electroplating solution preparation, detergent production), food industry (as sour agent, nutritional enhancer), pharmaceutical field (preparation of phosphate drugs) and detergents, coatings, ceramics and other industries.