Propriétés thermodynamiques des solutions liquides bromure de cuivre(I) - bromure de sodium et bromure de cuivre(I) - bromure de potassium à partir des équilibres liquide - solide

Abstract

Partial molar free enthalpies of mixing and activities of the components in molten solutions of the binary systems CuBr-NaBr and CuBr-KBr have been obtained from the liquidus lines. Both systems indicate negative deviations from ideality, the deviation being more pronounced with increasing size of the alkali metal cation. From the combined results of the integral free enthalpies of mixing and available data on the enthalpies of mixing, the entropies of mixing for the system CuBr-NaBr have been calculated and compared with those for the system CuCl-NaCl. The system CuBr-NaBr indicates positive excess entropies, twice as large as in the system CuCl-NaCl, except in the copper(I) bromide rich solutions (at concentrations above 65 mol%), where they become insignificant. These small excess entropies of mixing may result from the superionic character of the high temperature modifications of copper(I) bromide, having disordered structures.