Polyphosphoric Acid

Name:
Polyphosphoric Acid
Detailed information:
H_n2P_nO_3n+1, for n >1. Any of a series of strong acids, from pyrophosphoric acid, H₄P₂O₇ (n = 2), through metaphosphoric acid (large values of n).

Properties:

Viscous, water-white liquid. Water soluble. Does not crystallize on standing; hygroscopic. The commercial acid is a mixture of orthophosphoric acid with pyrophosphoric, triphosphoric, and higher acids and is sold on the basis of its calculated content of H3PO4, e.g., 115%. Superphosphoric acid is a similar mixture sold at 105% H3PO4. These acids revert slowly to orthophosphoric acid on dilution with water.

Hazard:

Toxic by ingestion; strong irritant.

Use:

Dehydrating, catalytic, and sequestering agents, for metal treating; many applications where a concentrated monooxidizing acid is needed; laboratory reagent.

See Phosphoric Acid.