Dielectric Properties of Aqueous Ionic Solutions. Parts I and II

TLDR

The dielectric constant of aqueous ionic solutions can be expressed as ε = εω + 2δc, with δ ranging from –7 to –15 for salts up to 2 M, and Part I discusses measurements and their relation to solution structure. Part II aims to evaluate the Debye–Sack saturation theory and the impact of reduced dielectric constant on the electrolytic properties of concentrated solutions. The study measured dielectric constants and loss angles of concentrated aqueous ionic solutions at wavelengths of 10 cm, 3 cm, and 1.25 cm. The Debye formula accurately predicts the static dielectric constant and relaxation time, which are lowered and shifted by all salts examined.

Abstract

The dielectric constants and loss angles of a series of concentrated aqueous ionic solutions have been measured at wave-lengths of 10 cm, 3 cm, and 1.25 cm. From these results the values of the static dielectric constant and relaxation time for these solutions have been calculated on the basis of the Debye formula, which appears to hold accurately. All salts show a lowering of the dielectric constant and a shift in the relaxation time of water. It is found that the dielectric constant ε can be represented by a formula ε=εω+2δ̄c, where εω is the dielectric constant of water, c is the concentration in moles per liter, and δ has values between −7 and −15 for various salts in concentrations of up to 2 M. In Part I the measurements are described and the results discussed in relation to the structure of ionic solutions. In Part II the validity of the Debye-Sack saturation theory of the dielectric constant and the effects of the fall of dielectric constant on the electrolytic properties of concentrated solutions are discussed.