Dielectric relaxation of aqueous electrolyte solutions. II. Ion-pair relaxation of 1:2, 2:1, and 2:2 electrolytes

Abstract

The low-frequency relaxation process contributing to the complex permittivity spectra of aq. solns. of MgSO4, CdSO4, Na2SO4, CdCl2, and CuCl2 is investigated. The dispersion amplitudes are analyzed with the help of model calcns., based on a modified Cavell equation for ellipsoidal bodies. Ion pairs are responsible for the low-frequency relaxation process with solvent sepd. ion pairs dominating for the sulfates, whereas contact ion pairs are formed by the chlorides. The obsd. relaxation time is analyzed as the superposition of chem. and reorientational relaxation. For the ion pairs, the effective vols. of rotation and the rate consts. of formation are detd. The results are compared with information from the literature.