Volumes and Heat Capacities of Dimethylsulfoxide, Acetone, and Acetamide in Water and of some Electrolytes in these Mixed Aqueous Solvents

Abstract

The densities and volumetric specific heats of binary mixtures of dimethylsulfoxide (DMSO), acetone (ACT), and acetamide (ACM) in water were measured at 25 °C with a flow densimeter and a flow microcalorimeter. The same properties were also determined for ternary mixtures of 0.1 m LiCl, NaCl, Me4NBr, and Bu4NBr in ACT–water and DMSO–water mixtures, and volumes for 0.1 m Bu4NBr in ACM–water and urea–water mixtures. The derived apparent molal volumes and heat capacities of nonelectrolytes in water and the transfer functions of the electrolytes from water to the mixed solvents suggest that, contrary to urea, the present non-electrolytes are slightly hydrophobic but, with the possible exception of ACT, their overall influence on water structure has practically no influence on the various solute–solute interactions.