Application of calorimetric methods to investigations of interactions in solutions

Abstract

The results of calorimetric measurements of dissolution enthalpy of electrolytes and nonelectrolytes in aqueous mixed solvents are discussed with regard to the intermolecular interactions that occur in the solution. Particular attention is given to the systems where hydrophobic hydration can play a significant role. Several ways for analysis of the Hydrophobic hydration effects are presented. In the case of the dissolution enthalpies of simple inorganic electrolyte in water-organic solvent mixtures a shape of the dependence of the standard dissolution enthalpy on the mixed solvent composition can serve as a source of information about the hydrophobic properties of the organic co-solvent. A quantitative measure of the hydrophobic properties of some organic compounds can be obtained from the analysis of the organic molecule-electrolyte (used here as a probe) enthalpic pair interaction coefficients in water, determined calorimetrically. In some cases, the 'cage model' can be used for determination of hydrophobic hydration energetic effect. This model has been applied in our laboratory for analysis of hydrophobic properties of crown ethers. It is noteworthy, that all presented methods lead to qualitatively consistent results. © 1999 IUPAC.