Volumetric and compressibility properties of liquid water as a solute in glycolic, propylene carbonate, and tetramethylurea solutions at T=298.15 K

The experimental measurements of the speed of sound and density in binary solutions of ethylene glycol, propylene glycol, propylene carbonate, and tetramethylurea (as solvents) and water as the solute in the concentration range of 0.1 mol.kg(-1) to 1 mol.kg(-1) at T = 298.15 K are reported. The data are used to obtain the isentropic compressibility (beta(S)) of solutions. The apparent molar volume (phi(v)) and compressibility (phi(KS)) of water at different concentrations of water are evaluated. The data of limiting partial molar volume (phi(circle)(v)) and compressibility (phi(circle)(KS)) of water and their concentration variation are examined to study the effect due to water-solvent and water-water interactions. It has been observed that there is a loss of volume as well as of compressibility of liquid water molecules in transferring them from the pure liquid state to a non-aqueous solvent except for propylene carbonate (in case of volumes). The data are compared with similar data obtained for water in alcohols and other apolar solvents like dioxane, acetonitrile, and dimethylformamide. A possible interpretation has been advanced on the basis of H-bonding characteristics and other structural details of the solvents and water to account for the effects due to water-water and water-solvent interactions. (C) 2007 Elsevier Ltd. All rights reserved.