Solutions of Electrolytes

Abstract

Due to limitations of both space and time, the reviewer has restricted the scope of the following review, omitting certain subjects which might properly be included. Notable among these are: solutions of electrolytes in molten metals and salts, solutions of polyelectrolytes and soaps, solutions of chelate complexes, phase studies with water as one component, ion exchange, elec trode processes, and nuclear magnetic resonance. These topics are left to reviews, under other titles, appearing at least occasionally in the Annual Review of Physical Chemistry.The reviewer does not disguise his enthusiasm for theoretical work, especially that with a statistical mechanical flavor.The most recent discussion of The Faraday Society, Interaction in Ionic Solutions (1), has been published. In this one volume a number of very sig nificant and stimulating articles are contained or discussed. Most of the papers are mentioned individually below. EQUILIBRIUM PROPERTIESTheory.-During the past year, considerable progress has been made in this field. Falkenhagen & Kelbg (2) have briefly reviewed recent work in the statistical theory of ionic solutions and have presented a derivation of the relation between the potential of average force and the mean electrostatic potential employed in the Debye-Huckel theory.A new theory which, for I-I electrolytes, has been carried through to a comparison with osmotic coefficient data is due to Moller (3). The starting point is the Born-Green integral equation in the multicomponent form previ ously presented by Kelbg & Moller (4). The Kirkwood superposition approxi mation is contained in the initial integral equations; other limitations are introduced while solving the equations, a process which contains some novel features. The initial equations are integral equations for the potential of average force, <par(r) -kTjur(r), on a particle of type T at a distance r from a central particle of type u. The first term <Pur(r) is the direct intermolecular potential ; the model is the usual one of charged hard sphere ions in a struc tureless solvent of macroscopic dielectric constant D. The unknown func tions farCr) also appear in the integrand as exp jar' In this theory these ex ponentials are linearized, then assumed to be slowly varying functions of distance, and, as a first approximation, replaced by a mean value € independ ent of the species (j and T. The equations are then solved for j�r(r) by using Fourier transforms along with the following approximations: all distances of closest approach are the same, a; exp <parCr) may be linearized in the inte-1 The survey of the literature was completed in Decemher, 1958. The Russian literature is par tly reviewed. 247 Annu. Rev. Phys. Chem. 1959.10:247-272. Downloaded from www.annualreviews.org by York University on 10/23/12. For personal use only. Quick links to online content Further ANNUAL REVIEWS