Monosodium Phosphate Anhydrous (CAS: 7558-80-7)

Monosodium phosphate (NaH2PO4), also known as anhydrous monobasic sodium phosphate and sodium

dihydrogen phosphate, is an inorganic compound ofsodium with dihydrogen phosphate (H2PO4-) anion.

One of many sodium phosphates, it is a common industrial chemical. It exists as an anhydrous salt, as well

as mono- and dihydrates.

Production and reactions

The salt is obtained by partial neutralization of phosphoric acid. The pKa of monosodium phosphate is 6.8-7.2

(depending on the physicochemical characteristics during pKa determination).

Heating this salt above 169 °C gives the corresponding sodium acid pyrophosphate:

2 NaH2PO4 → Na2H2P2O7 + H2O

Uses

Phosphates are often used in foods and in water treatment. The pH of such formulations is generally adjusted by

mixtures of various sodium phosphates, such as this salt. The sodium chloride equivalent value, or E-Value,

is 0.49. It is soluble in 4.5 parts water.