Solubility of Ca5{P04)3OH in the System Ca{OH)2-H3P04-H20 at 5, 15, 25, and 37 °C

Solubility isothe nns of hydroxyapatite, Ca5(PO.h OH (OHAp) , pre pa red by titrating a boiling aqueous suspe nsion of Ca(O HJ, with 0 .5 M H3PO., we re detennined in the te rnary system Ca(OHJ,-H3PO.-H20 at 5, 15, 25, a nd 3 7 C in the pH ra nge 3 .7-6. 7 by equilibration with dilute H3PO. solutio ns. The solubility product K" dete rmi ned as a fun ct io n of te mpe rature by a gene ra lized least-squa res procedure from 4 1 ex pe rimenta l points, is g ive n by the equation log K, = -82 19.41/ l' -1. 6657 -0.0982 151'.