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

Molar conductance of lithium acetate, sodium acetate and potassium acetate were studied in aqueous 2-butanol solutions with an alcohol mass fraction (w2) 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 (Λ0), association constants (KA,c) and cosphere diameter (R) for ion-pair formation. Gibbs energy (ΔG0), enthalpy (ΔH0) and entropy (ΔS0) for ion-association reaction were derived from the temperature dependence of KA,c. Activation energy for ionic movement (ΔH#) was derived from the temperature dependence of Λ0. Based on the composition dependence of Walden products (Λ0η0) and different thermodynamic properties (ΔG0,ΔH0, ΔS0 and ΔH#), 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.

► Molar conductance of some alkali metal acetates in aqueous 2-butanol solution.
► Sizes of the cations increase due to preferential solvation.
► Sizes of the solvated cations follow the crystallographic radii order.
► Alkali metal cations prefer water to 2-butanol in solvation or coordination sphere.