Ionic solvation in water + cosolvent mixtures. Part 9.—Free energies of transfer of single ions from water into water + ethanol mixtures

Abstract

Values for the free energy of transfer of the proton ΔG^°_t(H⁺) have been determined experimentally using spectrophotometric measurements on p-nitroaniline in water + ethanol employing the method previously used for other cosolvents mixed with water. Values for ΔG^°_t(i) for other individual ions, i= anion X^–, have been determined by combining these values for ΔG^°_t(H⁺) with values for ΔG^°_t(HX) calculated from electrochemical data. These values for ΔG^°_t(X^–) are subsequently used with values for ΔG^o_t(MX) and ΔG^°_t(MX₂) derived from electrochemical and solubility data to provide values for ΔG^°_t(M⁺) and ΔG^°_t(M²⁺). ΔG^°_t(X^–) and ΔG^°_t(X^2–) for anions where ΔG^°_t(HX) and ΔG^°_t(H₂X) are not available are calculated from ΔG^°_t(MX) and ΔG^°_t(M₂X) obtained from solubility measurements and the above values for ΔG^°_t(cation).