Sodium hydrogen phosphate, sodium hydrogen phosphate disodium, sodium hydrogen phosphate, chemical formula Na2HPO4, is one of the sodium salts produced by phosphoric acid. It is a deliquescent white powder, soluble in water, and the aqueous solution is weakly alkaline. Sodium monohydrogen phosphate is used as a water softener and additive in the food industry. It has a lot of hydrates:

Anhydrous matter - Na2HPO4 dihydrate - Na2HPO4·2H2O heptahydrate - Na2HPO4·7H2O dodecahydrate - Na2HPO4·12H2O

It can be neutralized from sodium hydroxide and phosphoric acid in a fixed dosimetric ratio:

2NaOH + H3PO4 → Na2HPO4 + 2H2O

It loses water above 240 ° C and decomposes into sodium pyrophosphate.

Appearance and properties: solid

Density: 1.064 g/mL at 20 °C

Boiling point: 158oC at 760mmHg

Melting point: 92,5°C

Stability: Stable. Incompatible with strong oxidizing agents.

Steam density: 4.9 (vs air)

Vapor pressure: 1.41mmHg at 25°C

Usage

Used as boiler water softener, weight gain agent for tanning leather, fabric, flame retardant for wood and paper, glaze and solder. A mordant for dyeing, used in the printing and dyeing industry as a stabilizer for hydrogen peroxide bleaching. It's used to make sodium pyrophosphate and other phosphates. It is also a culture agent for monosodium glutamate, erythromycin, penicillin, streptomycin and sewage biochemical treatment products. It not only has the use of sodium hydrogen phosphate dodecahydrate, but also can prevent caking in the process of transportation and storage.