7660. Potassium Phosphate, Tribasic

Nomenclature

CAS number: 7778-53-2
Phosphoric acid potassium salt (1:3); tripotassium phosphate.
K3O4P; mol wt 212.27.
K 55.26%, O 30.15%, P 14.59%.
K3PO4.

Description and references

Purification: J"anecke, Z. Phys. Chem. 127, 75 (1927); Simon, Schulze, Z. Anorg. Allg. Chem. 242, 331 (1939).

Properties

Deliquescent, orthorhombic crystals. d417 2.564. mp 1340°. Soly in water: 43.7% at 0°; 50.8% at 25°; 59.7% at 45.1°. Insol in alcohol. Aq solns are strongly alkaline.

Derivative

Heptahydrate.

Nomenclature

CAS number: 22763-02-6
K3O4P.7H2O; mol wt 338.37.
K 34.66%, O 52.01%, P 9.15%, H 4.17%.

Derivative

Octahydrate.
K3O4P.8H2O; mol wt 356.39.
K 32.91%, O 53.87%, P 8.69%, H 4.53%.

Properties

Flat, rectangular platelets, mp 45.1°.

Use

Buffering agent.