Ion Polarizabilities in Binary Liquid Mixtures of Water/Organic Solvents

Using our recently proposed method to obtain salt and ion polarizabilities in aqueous solutions, we determine the polarizabilities of five salts (LiCl, NaCl, NaBr, KBr, and MgSO₄) in water-acetonitrile, water-ethanol, and water-acetone solutions at eight different water-organic solvent compositions at the D-line of sodium (589.3 ± 0.1 nm). Setting Li⁺ as the reference ion, we determine the ion polarizabilities of Na⁺, Cl^-, and Br^- in binary liquid mixtures. Our results show that cation polarizability is nearly unaffected by solvent composition, but anion polarizability exhibits a nonmonotonic behavior with increasing mole fraction of the organic component in the liquid mixture. This suggests that ion polarizability in a solution is affected by the solvent. The results of salt and ion polarizabilities can be used as important reference data for physical chemistry, atmospheric science, and biophysics.