Thermodynamic parameters of transfer and solution of oxalic acid in dimethylsulphoxide-water media

Abstract

The solubility measurements for oxalic acid in DMSO-H 2O mixtures have been performed at four temperatures (298.15, 303.15, 308.15 and 313.15 K) to calculate the thermodynamic parameters of solution and transfer of oxalic acid from water, as reference solvent, to DMSO-H 2O mixed solvent. The solubility data have been discussed in terms of the solubility parameters. A multiple linear regression method, known as the extended Hansen solubility approach, has been used to estimate the partial and total solubility parameters for oxalic acid. The activity coefficients of oxalic acid in water and mixed solvents have been calculated theoretically and found to be unity. The thermodynamic parameters of transfer of oxalic acid have been found to increase with increasing mole fraction of DMSO. The electrostatic parts of the standard free energies of transfer for oxalic acid have been calculated theoretically. These values increase with increasing DMSO content.