8660. Sodium Phosphate, Monobasic

Nomenclature

CAS number: 7558-80-7
Phosphoric acid sodium salt (1:1); sodium biphosphate; sodium dihydrogen phosphate; acid sodium phosphate; monosodium orthophosphate; primary sodium phosphate.
H2NaO4P; mol wt 119.98.
H 1.68%, Na 19.16%, O 53.34%, P 25.82%.
NaH2PO4.

Description and references

It is about 99% pure.

Derivative

Monohydrate.

Nomenclature

CAS number: 10049-21-5
H2NaO4P.H2O; mol wt 137.99.
H 2.92%, Na 16.66%, O 57.97%, P 22.45%.

Properties

White, odorless, slightly deliquesc crystals or granules. At 100° loses all its water; when ignited it converts into metaphosphate. Freely sol in water; practically insol in alcohol. The aq soln is acid. pH of 0.1 molar aq soln at 25°: 4.5.

Derivative

Dihydrate.

Nomenclature

CAS number: 13472-35-0
H2NaO4P.2H2O; mol wt 156.01.
H 3.88%, Na 14.74%, O 61.53%, P 19.85%.

Properties

Orthorhombic bisphenoidal colorless crystals, mp 60°. d 1.915. At room temp crystallizes with 2H2O. Directions for max yield: Beans, Kiehl, J. Am. Chem. Soc. 49, 1878 (1927).

Use

In baking powders; in boiler water treatment; as dry acidulant and sequestrant for foods: Tidridge, Pals, US 3030213 (1962 to FMC). Buffering agent.

Therapeutic Category

Urinary acidifier.

Therapeutic Category (Veterinary)

Urinary acidifier.