The Composition of Strong Phosphoric Acids

Publisher Website
Google Scholar
Abstract
The strong phosphoric acids in the range from 67 to 80 wt. % phosphorus (V) oxide were analyzed by the anion-exchange chromatography combined with the usual molybdenum-blue colorimetry. The so-called “ 300°C-strong phosphoric acid” which has been used for many analytical purposes in the authors’ laboratory is composed of 44.4 wt. % orthophosphoric acid, 39.8 wt. % pyrophosphoric acid, 12.3 wt. % tripolyphosphoric acid, and 3.6 wt. % tetrapolyphosphoric acid. It was found that the relation of mole fractions of middle PO4 units, end PO4 units, orthophosphoric acid units, and unreacted water molecule units versus the mole ratio H2O/ P2O5 agrees with the reorganization theory for the strong phosphoric acids, presented by Parks and Van Wazer.