Ion association and solvation behavior of some alkali metal acetates in aqueous 2-butanol solutions at T = 298.15, 303.15 and 308.15 K

Abstract

Molar conductance of lithium acetate, sodium acetate and potassium acetate were studied in aqueous 2-butanol solutions with an alcohol mass fraction ( w 2) of 0.70, 0.80 and 0.90 at 298.15, 303.15 and 308.15 K. The conductance data were analyzed with the Fuoss conductance–concentration equation to evaluate the limiting molar conductances ( Λ 0), association constants ( K A, c ) and cosphere diameter ( R) for ion-pair formation. Gibbs energy (Δ G 0), enthalpy (Δ H 0) and entropy (Δ S 0) for ion-association reaction were derived from the temperature dependence of K A, c . Activation energy for ionic movement (Δ H #) was derived from the temperature dependence of Λ 0. Based on the composition dependence of Walden products ( Λ 0 η 0) and different thermodynamic properties (Δ G 0,Δ H 0, Δ S 0 and Δ H #), the influence of the solvent composition on ion-association and solvation behavior of ions were discussed in terms of ion–solvent, ion–ion interactions and the structural changes in the mixed solvent media.