Electrolyte Molar Volumes at 273-373-K in Propylene Carbonate, N-Methylformamide, Formamide and Methanol: Their Relation to Solvent Compressibility. Ion Association Constants in Acetonitrile at 298-K

Abstract

Measurements have been made on several electrolytes of their apparent molar volumes at 25°C by dilatometry and typically from 0°C to 125°C by expansimetry in propylene carbonate, N- methylformamide, formamide, and methanol. The electrolyte limiting apparent molar volumes are shown to be linearly related to the temperature dependent isothermal compressibility in these solvents, as in water. Ion-pair equilibrium associated constants have been determined by volumetric means for NH4SCN, KSCN and ten other electrolytes in acetonitrile at 25°C and similarly for MgSO4 in water at 25°C. Less extensive apparent molar volume studies in water 0 to 160°C for high charge species and in liquid sulfur dioxide at 25° are also reported.