The volumetric analysis of phosphates

A method has been developed for the volumetric determination of orthophosphate, and a simple variation permits the determination of the average number of phosphorus atoms per molecule in condensed phosphates. For total P₂O₅ the phosphates are converted to the diacid orthosalt and precipitated as silver phosphate. The liberated acid is then titrated. For determination of chain length the condensed phosphate is converted to the diacid form and treated similarly, then hydrolysed and determined as orthophosphate. The ratio of the two titrations is equal to the average number of phosphorus atoms per molecule.