Monosodium phosphate

Monosodium phosphate, also known as monobasic sodium phosphate and sodium dihydrogen phosphate, is an inorganic compound with the chemical formula. It is a sodium salt of phosphoric acid. It consists of sodium cations and dihydrogen phosphate anions. One of many sodium phosphates, it is a common industrial chemical. The salt exists in an anhydrous form, as well as monohydrate and dihydrate.

Production and reactions

The salt is obtained by partial neutralization of phosphoric acid.
The pK_a of monosodium phosphate is 6.8-7.2.
Heating this salt above 169 °C gives disodium pyrophosphate:
When heated at 550 °C, anhydrous trisodium trimetaphosphate is formed:

Uses

Phosphates are often used in foods and in water treatment. The pH of such formulations is adjusted by mixtures of various sodium phosphates, such as this salt. It is added in animal feed for its nutritional value.