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-pentanediol (1,2PeD) and NaI in aqueous solutions of 1,2-ethanediol and 1,2-propanediol were measured within the whole available range of salt concentrations. The standard enthalpies of solution ΔsolH1α vs. mixed solvent composition exhibit their maxima in the water-rich region of all investigated mixtures. The positions and heights of maxima depend on the kind of electrolyte and the size of diol molecule, suggesting that the maxima are due to hydrophobic interactions. The analysis of obtained ΔsolHα values and of the literature data concerning the systems with alcohols and alkoxyethanols suggests that there is a similarity of the ΔsolHα = f(composition) curves. Enthalpic pair interaction coefficients, hxy, for 1,2-diol-NaCl in water were calculated and analyzed.