SOLUTION ENTHALPIES OF NACL AND NAI IN WATER WITH 1,2-ETHANEDIOL, 1,2-PROPANEDIOL, 1,2-BUTANEDIOL AND 1,2-PENTANEDIOL AT 298.15 K

The dissolution heats of NaCl in aqueous solutions of 1,2-ethanediol ( 1,2ED), 1,2-propanediol (1,2PD), 1,2-butanediol (1,2BD) and 1,2-pentan ediol (1,2PeD) and NaI in aqueous solutions of 1,2-ethanediol and I,2- propanediol were measured within the whole available range of salt con centrations. The standard enthalpies of solution Delta(sol)H(l)(propor tional to) vs. mixed solvent composition exhibit their maxima in the w ater-rich region of all investigated mixtures. The positions and heigh ts of maxima depend on the kind of electrolyte and the size of diol mo lecule, suggesting that the maxima are due to hydrophobic interactions . The analysis of obtained Delta(sol)H(proportional to) values and of the literature data concerning the systems with alcohols and alkoxyeth anols suggests that there is a similarity of the Delta(sol)H(proportio nal to) = f(composition) curves. Enthalpic pair interaction coefficien ts, h(xy),,, for 1,2-diol-NaCl in water were calculated and analyzed. (C) 1997 Elsevier Science B.V.