Thermodynamic studies of some non-electrolytes in aqueous solutions at low temperatures

The experimental data of density (ρ) and speed of sound (u) in the temperature range (275.15 to 283.15) K have been obtained for aqueous solutions of di-methyl sulphoxide (DMSO), ethylene di-amine (EDA), polyethylene glycol-200 (PEG-200) and polyethylene glycol-400 (PEG-400). The specific heat (Cp) data for aqueous solutions of DMSO, EDA, and PEG-200 have also been obtained at T = 279.15 K. The data obtained are used to calculate the derived parameters like isentropic compressibility (βS), isothermal compressibility (βT), apparent molar volume (ϕV), coefficient of thermal expansion (α), apparent molar isentropic compressibility (ϕKS), and internal pressure (Pi). The limiting values of apparent molar volume (ϕV∘) and apparent molar isentropic compressibility (ϕKS∘) were also obtained. From these data, the temperature coefficients of limiting properties were computed. The results obtained were interpreted in terms of solute–solvent and solute–solute interactions and structure making and structure braking abilities of the solute. The results of Pi are used to discuss the extent of hydrogen bonding between solute and solvent (water).