Solubility of Phosphates, Rates of Solution of Calcium Phosphates in Phosphoric Acid Solutions

Abstract

Information about the complex chemistry of phosphate in soil systems was obtained from measurements of the rates of solution of eight synthetic calcium phosphates and three natural fluorapatites in dilute solutions of phosphoric acid. The rates of solution vary inversely with the pH of the solvent. The effects of temperature and stirring show that the rates for the calcium orthophosphates are controlled by diffusion, and approximate diffusion coefficients are presented. The rate for vitreous calcium metaphosphate is controlled by chemical reaction, probably hydrolytic degradation. © 1957, American Chemical Society. All rights reserved.