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EXCESS PARTIAL MOLAR ENTHALPIES, ENTROPIES, GIBBS ENERGIES, AND VOLUMES IN AQUEOUS DIMETHYLSULFOXIDE

TitleEXCESS PARTIAL MOLAR ENTHALPIES, ENTROPIES, GIBBS ENERGIES, AND VOLUMES IN AQUEOUS DIMETHYLSULFOXIDE
Publication TypeJournal Article
Year of Publication1995
AuthorsLai, JTW, Lau, FW, Robb, D, Westh, P, Nielsen, G, Trandum, C, Hvidt, A, Koga, Y
JournalJournal of Solution Chemistry
Volume24
Pagination89-102
Date PublishedJan
Type of ArticleArticle
ISBN Number0095-9782
Keywords2-BUTOXYETHANOL, 25-DEGREES-C, AQUEOUS DIMETHYLSULFOXIDE, DIMETHYL-SULFOXIDE, ENTROPIES, excess partial molar enthalpies, GIBBS ENERGIES AND VOLUMES, HEAT-CAPACITIES, LIQUID-MIXTURES, MIXING SCHEME, RANGE, SOLUTE-SOLUTE INTERACTION, TRANSITION, WATER-RICH REGION
Abstract

The excess partial molar enthalpies, the vapor pressures, and the densities of dimethylsulfoxide (DMSO) - H2O mixtures were measured and the excess partial molar Gibbs energies and the partial molar volumes were calculated for DMSO and for H2O. The values of the excess partial molar Gibbs energies for both DMSO and H2O are negative over the entire composition range. The results for the water-rich region indicated that the presence of DMSO enhances the hydrogen bond network of H2O. Unlike monohydric alcohols, however, the solute-solute interaction is repulsive in terms of the Gibbs energy. This was a result of the fact that the repulsion among solutes in terms of enthalpy surpassed the attraction in terms of entropy. The data in the DMSO-rich region suggest that DMSO molecules form clusters which protect H2O molecules from exposure to the nonpolar alkyl groups of DMSO.

URL<Go to ISI>://A1995QF27900007