Thermodynamics of transfer of electrolytes and ions from water to aqueous solutions of polyhydroxy compounds

The free energies, entropies and enthalpies of transfer of tetraphenylarsonium benzoate (Ph4AsBz), tetraphenylarsonium picrate (Ph4AsPi), potassium tetraphenylboride (KPh4B), silver picrate (AgPi) and potassium picrate (KPi) from water to aqueous solutions of mannitol, sorbitol and sucrose have been determined from solubility product (Ksp) measurements of these salts at different temperatures. The transfer values for the constituting ions have been evaluated using the TATB assumption. Values of ΔG0t for the cations and anions of these salts indicate that these ions are destabilized in these media. ΔS0t and ΔH0t for the ions indicate that these polyhydroxy compounds break the water structure and structure breaking ability follows the sequence sucrose > sorbitol > mannitol. The results have been explained in terms of the overlap cospheres model of solute/ion hydration.