Disodium pyrophosphate, also known as sodium acid pyrophosphate (SAPP), is an inorganic compound that is used in many ways, including as a food additive: 
Chemical composition
Disodium pyrophosphate is made up of sodium cations (Na+) and dihydrogen pyrophosphate anions (H2P2O7-). Its chemical formula is Na2H2P2O7, and its molar mass is 221.94 g/m.
 
Chemical Formula: Na₂H₂P₂O₇
Molecular Weight: Approximately 219.88 g/mol.
Appearance: Typically exists as a white, crystalline powder.
Solubility: Soluble in water, with limited solubility in alcohols
Food Industry: Often used as a leavening agent in baked goods and as a preservative. It helps in maintaining texture and stability.
Industrial Applications: Utilized in detergents, ceramics, and as a buffering agent in various chemical reactions.
Analytical Chemistry: Sometimes used as a reagent in laboratory settings.
CAS>NO :   7758-16-9.
Detergents: Acts as a builder in detergents, improving cleaning efficiency.
Ceramics: Used in the manufacture of ceramics and glazes.
Buffering Agent: Helps maintain pH levels in chemical processes.