The Physical Chemistry of Electrolytic Solutions

Abstract

Shortly after the enunciation of the theory of electrolytic dissociation by Arrhenius, it became evident that strong electrolytes behaved in an apparently anomalous manner, and in spite of many attempts to develop empirical rquations to represent the properties of such solutions little progress was made. The introduction of the activity concept by G.N. Lewis and the discovery of the ionic strength principle by Lewis and Randall provided a much needed impetus to the study of the thermodynamic properties of electrolytes, both strong and weak, but a sound theoretical basis, which would permit a systematization of the results, was lacking. The publication of the Debye-Hueckel theory of interionic attraction in 1923 thus marked the commencement of a new era in the study of electrolytic solutions, and the past 20 years have seen the development of a considerable literature dealing with the physical chemistry of electrolytes. Among the outstanding contributors to this literature has been the group of researchers at Yale University, directed by Professor Herbert S. Harned, whose work has been marked by its exceptional thoroughness and accuracy. The book under review is a monograph by Professor Harned and his collaborator Professor Owen, on the physical chemistry of electrolytic solutions; in view of their own important contributions to the subject, it is a book which they are supremely qualified to write. The authors contend that the interionic attraction theory is so well established as to permit the development of the purely theoretical aspects before the discussion of the experimental results. Consequently, in constructing the book the somewhat unusual procedure has been adopted of presenting the basic theory fist, and following this with a critical discussion of the data in the light of the theory. In an advanced treatise of this kind such a presentation undoubtedly has many advantages. The material of the book falls into three main sections, the first of which, as just indicated, constitutes a theoretical introduction to the subject of electrolytic solutions. The abbreviated titles of the chapters are as follows: General Thermodynamic Introduction; Interionic Attraction Theory; Thermodynamic Properties of Solutions; Theory of Irreversible Processes; and Numerical Compilations. The physical constants used in connection with the latter differ from those now generally accepted; the authors explain this by the fact that the numerical calculations have extended over a period of years. It would have been an advantage, however, if some of the values, such as the Debye constants, had been recalculated so as to conform with the newer values of the electronic charge and the Avogadro number. The second section contains a discussion of the experimental results from the aspect of the individual physicochemical properties; the chapters are entitled: Irreversible Processes (Conduction, Transference Numbers, Viscosity, and Diffusion); Coulomb Forces and Ion Association; Thermochemical Quantities; Activity and Osmotic Coefficients; and Galvanic Cells. It may be remarked that no attempt is made to give details of experimental technique; the methods are described briefly, however, and there are full references to the literature. Most of the space is devoted to a consideration of the results, especially in relation to the theory developed in the earlier chapters. The last portion of the book deals with the experimental data from the point of view of the electrolytes themselves, rather than from that of the methods of investigation. The chapter headings are: Hydrochloric Acid; Strong 1-1 Electrolytes; Polyvalent Electrolytes; Mixtures of Strong Electrolytes; and Weak Electrolytes. The work is concluded with an appendix containing many tables of data. Attention may be called to the complete omission of the theory of dipolar ions on the grounds that the subject is treated in another volume of the same series of monographs. The book is replete throughout with references to the literature, tables, and figures. It is the most comprehensive and authoritative treatise in its field yet published, and it is likely to remain the standard work for many years to come. For this reason, in particular, it is unfortunate that some discussion of dipolar ions was not included, and that an effort was not made to recalculate certain results on the basis of the accepted values of physical constants. Because of its complete and detailed nature, this is not a hook to be read lightly. The authors think it necessary to apologize for the fact that continuous reading of certain portions of the text may he found tedious or tiresome. They need not be concerned on this score, for there are very few chemists who will be able to read more than a few pages at one sitting. The mathematics is by no means easy, and the complexity of the subject is indicated to some extent by the glossary of symbols which occupies over 13 pages! However, in the opinion of the reviewer the prime function of the book is as a work of reference; as such it is a significant contribution to the literature of physical chemistry of which the authors, the editors of the series of monographs, and the publishers may well be proud.