Interaction Studies of Calcium Dihydrogen Phosphate with Sulphate Salt

The interaction of calcium dihydrogen phosphate with copper, zinc and cobalt sulfate salts in dilute solutions (0.01 M) at 303.15 and 353.15 K, depending on the Ca(H2PO4)2:MSO4 ratio, was studied. It is found that at a molar ratio of 1:1, the pH, electrical conductivity, viscosity and density have extreme values, which indicates a change in the composition of solutions. The results of chemical analysis at a ratio of of 1:1 showed the formation of calcium sulfate and hydrogen phosphates of copper, zinc and cobalt, regardless of temperature. This indicates that calcium dihydrogen phosphate undergoes hydrolysis in an aqueous medium and then an exchange reaction occurs between microelement sulfates and calcium hydrogen phosphate. The addition of phosphoric acid into mixing solutions prevents the hydrolysis of calcium dihydrogen phosphate and the reaction products were calcium sulfate and dihydrophosphates of copper, zinc and cobalt.