Determination of the absolute values of Gibbs energy of hydration or solvation ΔG0 abs(M+ or X-)h or s of monovalent (alkali metal and halide) ions and other thermodynamic parameters in aqueous and non-aqueous solvents using a single standard state and analysis of ΔG0 abs(M+ or X-)h or s values based on cluster-ion solvation method

Abstract

or X - ) h or s and other thermodynamic parameters in aqueous and non-aqueous solvents (methanol, ethanol, n-propanol, isopropanol, n-butanol, ethylene glycol, propylene carbonate (PC), N-methyl formamide (NMF), acetone, tetrahydrofuran (THF), 1,4-dioxan, acetonitrile) were determined directly using modified Born equation and a single standard state [i.e. AG° and ΔH 0 (but not ΔS 0 ) of H 2 gas and other elements to be zero in their elementary standard states at 1 atm. pressure (1 bar) and 298 K]. The ΔH 0 abs (M + or X - ) h or s and ΔG 0 (M + or X - ) h or s values are calculated considering ion-dipole, ion-quadrupole interactions and without considering the interaction terms. Very few data are available in non-aqueous solvents for comparison. Most of the single ion values (particularly for the anions) suffer from limitations associated with the erroneous principle of division of solvation energies ΔG 0 h or s (MX) or ΔΗ 0 h or s (MX) of electrolytes into single ion values. ΔG 0 (M + or X - ) h values determined using cluster-ion solvation data have also been presented. The values have been claimed to be most accurate in recent years. However, the method involves a number of assumptions of doubtful validity and the values cannot be regarded to be equivalent to ΔG 0 (Μ + or X - ) h or determined by other workers using different methods. Coupling the values of ΔG 0 (M + or X - ) h or s and ΔH 0 (M + or X - ) h or s with ΔG 0 (M + or X - ) g and ΔH 0 (M + or X - ) g values in the gaseous state, ΔG 0 (M + or X - ) Water or org. solvent' ΔH 0 (Μ + or X - ) water or org. solvent and ΔS 0 (M + or X - ) water or org. solvent [values in water and in organic solvents] are determined.