Thermodynamic investigation of ZnMoO4 (s) and Zn3Mo2O9 (s) compounds

Present study investigates the calorimetric and thermodynamic properties of ternary zinc molybdates, namely, ZnMoO4 (s) and Zn3Mo2O9 (s). A high temperature calorimeter is employed for measuring the enthalpy incre-ment and enthalpy of dissolution of Zn-Mo-O compounds. The variation of molar heat capacities of ZnMoO4 (s) and Zn3Mo2O9 (s) (deduced from the enthalpy increment data) with temperature can be expressed as follows: The standard molar enthalpies of formation of ZnMoO4 (s) and Zn3Mo2O9 (s) are determined employing 3Na2O.4MoO3 as the calorimetric solvent and the corresponding values are found to be-1137.51 +/- 1.7 and-2616.47 +/- 4.5 kJ mol-1 , respectively for ZnMoO4 (s) and Zn3Mo2O9 (s). These new experimental results coupled with the literature data are employed for generating thermodynamic functions of these compounds.