NaH2PO4

Sodium dihydrogen phosphate, with the chemical formula NaH2PO4, is an inorganic compound. It is a salt of sodium and phosphoric acid. It can exist in anhydrous form or as a monohydrate (NaH2PO4·H2O). It is also known by several other names, including monosodium phosphate, sodium phosphate monobasic, and phosphoric acid monosodium salt.

NaH2PO4 is a white crystalline solid that is soluble in water. In aqueous solutions, it acts as a weak acid. It is a component of the phosphate buffer system, which helps maintain pH balance in biological and chemical systems. Its ability to act as a buffering agent is due to the equilibrium between the dihydrogen phosphate ion (H2PO4-) and the hydrogen phosphate ion (HPO4^2-).

The compound finds numerous applications. In the food industry, it is used as a food additive, often designated as E339(i), serving as an acidity regulator, emulsifier, and sequestrant. It is also used in water treatment to prevent corrosion and scale formation. In pharmaceuticals, it can be found in laxatives and as an excipient in tablet formulations. Additionally, it is used in detergents, textile processing, and as a laboratory reagent.