Thermodynamics of chlorination reactions of some metal selenides

Abstract

For the reactions of silver, copper, zinc, lead, manganese, cadmium and tin selenides with chlorine, which occur according to the equations MeSe + 3 2 Cl 2 = MeCl 2 + 1 2 Se 2 Cl 2 MeSe + 3Cl 2 = MeCl 2 + SeCl 4, the standard free energy changes as a function of temperature have been calculated and the results obtained discussed. An attempt has been made to simplify the formulae for ΔG 0 T of the reaction as a function of the temperature. Using established fivenomial equations, the values of ΔG 0 T for the reactions have been calculated by means of a ODRA 1003 computer; linear formulae were found for these values by the least-squares technique and can be represented by ΔG 0 T = a + b × T. The calculated ΔG 0 298 values (for the chlorination of some metal selenides) have been compared with the values found for the chlorination of the oxides, sulphides and tellurides of the same metals. It has been shown, by comparison of the following reactions: MeO + Cl 2 = MeCl 2 + 1 2 O 2 MeS + Cl 2 = MeCl 2 + 1 2 S 2 MeSe + 3Cl 2 = MeCl 2 + SeCl 4MeTe + 3Cl 2 = MeCl 2 + TeCl 4 that the ΔG 0 298 of the compounds of the same metal depends linearly on the logarithm of the molecular weight of the chlorinated compound, MeX. Furthermore, the ΔG 0 298 values of the chlorination reactions of MeX compounds depend linearly on the atomic number of the element X.