Effect of non-electrolyte properties on the enthalpic interaction coefficients for NaCl/Nal–non-electrolyte pairs in water. Dissolution enthalpies of NaCl and Nal in aqueous solutions of butan-2-one and 1,2-dimethoxyethane at 25 °C

Abstract

Dissolution enthalpies of NaCl and Nal in aqueous solutions of butan-2-one and 1,2-dimethoxyethane have been measured and appropriate enthalpic pair interaction coefficients, h_xy(electrolyte–non-electrolyte) in water have been determined. These results along with the other data concerning the NaCl–non-electrolyte and Nal–non-electrolyte pairs taken from our earlier reports and from the literature, were analysed with respect to the effect of the non-electrolyte properties on variations of the h_xy values in water. The h_xy coefficients for both NaCl–nonelectrolyte and Nal–non-electrolyte systems are linearly correlated with the heat capacity of the non-electrolyte interaction with solvent water.

The group contributions illustrating the interactions between the electrolyte (NaCl or Nal) and CH₂, OH, O, CO, ‘Pep’ and ‘iPep’ groups in the non-electrolyte molecules were calculated and discussed from the viewpoint of a competition between the solute–solute and solute–solvent interactions.

The analysed enthalpic pair interaction coefficients are well correlated through the multiparameter equation of the Abraham–Kamlet–Taft type.