Outlines of a New System of Thermodynamic Chemistry

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. In the rapid development of theoretical chemistry, in which the two laws of energy have played so important a r?le, two thermody namic methods have been widely used. The first, employed by Gibbs, Duhem, Planck, and others, is based on the fundamental equations of entropy and the thermodynamic potential. The second, employed by such men as van't Hoff, Ostwald, Nernst, and Arrhenius, consists in the direct application to special problems of the so-called cyclic process. The first method is general and exact, and has been a favorite with mathematicians and physicists, those who were already familiar with the use of the potential theory in mechanics. But unfortunately, ex cept in name there is little analogy between physico-chemical equi librium and the equilibrium in a mechanical system, and it is perhaps for this reason that the method has failed to commend itself to the majority of chemists. It must be admitted that it is the second method to which we owe nearly all of the advances that have been made during the last thirty years through the application of thermody namics to chemical problems, and which is now chiefly used by inves tigators and in the text-books of physical chemistry. Yet the application of this method has been unsystematic and often inexact, and has produced a large number of disconnected equations, largely of an approximate character. An inspection of any treatise on physical chemistry shows that the majority of the laws and equations obtained by the application of thermodynamics, are qualified by the assumption that some vapor behaves like a perfect gas, or some solu This content downloaded from 192.38.88.136 on Mon, 11 Apr 2016 14:46:33 UTC All use subject to http://about.jstor.org/terms 260 PROCEEDINGS OF THE AMERICAN ACADEMY. tion like a perfect solution.1 As examples may be cited the mass law, the law of change of solubility with the temperature, the law of the lowering of vapor pressure by a solute, the law of Nernst for the electromotive force of a concentration cell, and many other equally im portant generalizations. It is probable that no one of these laws is ever strictly true. As approximations to the truth they have been of the greatest service. But now that their utility has been demonstrated, the attention of a progressive science cannot rest upon their acknowledged triumphs, but must turn to the investigation of their inaccuracies and their limi