Sodium pyrophosphate usually exists in two forms, decahydrate and anhydrous. Tetrasodium pyrophosphate is more widely used. Food grade sodium pyrophosphate is a common legal food additive in food, while industrial grade sodium pyrophosphate is widely used in water treatment, printing and dyeing, washing and other industries.

Na₄P₂O₇.10H₂O, molecular formula of sodium pyrophosphate decahydrate, relative molecular weight 446.07, decahydrate is colorless or white crystalline or crystalline powder.

Tetrasodium pyrophosphate molecular formula Na₄P₂O₇, relative molecular weight 265.90, anhydrous substance is white powder, soluble in water, insoluble in ethanol and other organic solvents.

The quality requirement of sodium pyrophosphate is relatively high. The sodium pyrophosphate of Chuandong Chemical Group uses hot acid as raw material, so it is called thermal acid process. The process is: using soda ash or caustic soda with industrial phosphoric acid or food grade phosphoric acid or low arsenic. The phosphoric acid is neutralized, and the industrial grade or food grade tetrasodium pyrophosphate is obtained by dry dehydration and high temperature polymerization.

Tetrasodium pyrophosphate is a white crystalline powder. The relative density of melting point is 2.534 at 880°C. The solubility in water is 6.23g at 20°C. The water solution is alkaline and insoluble in alcohol. Whether industrial or food grade sodium pyrophosphate, the use of anhydrous substance is greater than that of sodium pyrophosphate decahydrate.