The polarizabilities of species present in ionic solutions

Abstract

Values for the polarizabilities of both mono and multinuclear anions in aqueous solution at infinite dilution are derived. This is achieved by subtracting from each experimentally determined molar polarizability, the polarizability of the cation as well as the total change caused by this cation in the polarizabilities of neighbouring water molecules. Each cation polarizability was taken to be unchanged from its value known from previous work to be common to both the free ion and the ion in an ionic crystal. The required values of the total changes in the polarizabilities of water molecules influenced by cations are derived from the experimental molar polarizabilities by two different methods. The first of these yields results which are essentially identical to those derived from the second approach in which the value for Li+ is fixed from ab initio quantum chemistry computations including electron correlation effects. The polarizability of each anion in aqueous solution is found to be considerably reduced from that of the free ion and to be close to that of the anion in its solid caesium salt.