Solubility of -Ca3(PO4)2 in the system Ca(OH)2-H3PO4-H2O at 5, 15, 25, and 37 C

Solu bility isoth erms of beta-trica lcium phos ph ate, j3-Ca3(PO.)" prepared by heating mixtures of CaC0 3 an d CaHP O. above 800 C, were dete rmined in th e tern ary system Ca(OH),H 3PO.-H 20 a t 5, 15,25, and 37C in the pH range 6.0-7.5 by equilibrati on with dilute H 3PO ., solutions. The results in dicate that j3-Ca3(P0 4), has a negative therm al coefficien t of solu bility. The solubility produ ct , K" was de termin ed as a fun cti on of te mperature by a ge neral ized least-s qu a res procedure; the res ultin g equ ation is log Ks =-45723. 26/T + 287.4536 -0. 546763 T;