Densities and Excess Volumes of Fused Halides

Densities of molten AgBr-AX (A = Li, Na, K, Rb, Cs; X = Br or CI), AgBr-AgCl, KBr-NaBr, KBr-CsBr, KCl-KBr, and KCl-CsBr mixtures have been measured at 0.5 mole fraction using the method of Archimedean displacement. The excess volumes of mixing are all positive, except for the AgBr-LiBr system. Attempts to relate the excess volumes of the binary AgBr-ABr systems to the second order conformal solution theory of Reiss, Katz, and Kleppa are unsuccessful, since VE is large even when the diameter difference parameter, Ö12, is close to zero. However, the excess volumes of the reciprocal AgBr-ACl systems at 0.5 mole fraction are found, within experimental error, to have a linear dependence on S12. The positive deviations from conformal solution theory which occur for the alkali halide mixtures have been interpreted in terms of non-Coulombic polarisation and van der Waals interactions.