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Thermodynamics of Solvation and Apparent Molar Volumes for O-Toluic Acid in Ethanol-Water Mixtures At 298.15K

Esam A Gomaa , Elsayed M Abou Elleef , Kamal M Ibrahim, Amr A Ibrahim1and Maii S Mashaly

The solubilities of o-toluic acid have been determined in water and ethanol-water mixtures at different temperatures. From the solubility data, the values of the solubility product of o-toluic acid were calculated, and from these values, Gibbs energy for the solution processes was determined. The respective thermodynamic functions for mixing and solvation processes as well as the activity coefficients for the solute were calculated. In addition, the thermodynamic quantities for the transfer process of o-toluic acid from water to ethanol-water mixtures were also calculated in order to estimate the non-ideality due to the mean activity coefficient of ions, contributions of hydrogen-bonds or of other dipolar interactions. The molar, Van der Waals, electrostriction and apparent molar volumes of o-toluic acid in various solvents at 298.15K are also calculated. The results are discussed on the basis of transfer functions and in terms of solute- solute and solute-solvent interactions.