On Simple Gas Reactions

Abstract

[Following the publication of Arrhenius's paper (Paper 2) on the significance of the temperature dependence of the rates of chemical reactions, a number of workers interested themselves in the problem of the significance of the activation energy. With the advent, in the nineteen-twenties, of the new quantum mechanics it was natural to see to what extent activation energies could be calculated by the same methods that were beginning to be used for the calculation of the energies of stable molecules. The most successful of the early attempts of this kind was that described in the paper reproduced in part below. In it Eyring and Polanyi show that a reasonable estimate of the activation energy of a reaction involving three atoms can be obtained by applying quantum-mechanical procedures with some assistance from empirical methods. A particularly important feature of the Eyring–Polanyi work is their use of potential-energy surfaces, which provide a very valuable pictorial representation of the course of a chemical reaction. Henry Eyring was born in 1901, and at the time this paper was written was a (U.S.) National Research Fellow in Berlin. Later he became Professor of Chemistry at Princeton University and is now Dean of the Graduate School at the University of Utah. He has made many distinguished contributions, particularly in the application of theoretical methods, to the understanding of the rates of chemical and physical processes. Perhaps his most pioneering work is represented by the present paper and by Paper 5, which deals with the application of statistical methods to the rates of chemical reactions. Michael Polanyi was born in 1891 in Budapest, and at the time this paper was written was a member of the Kaiser Wilhelm Institut fur Physikalische Chemie in Berlin. He was later Professor of Physical Chemistry at Manchester University, and in 1948 became Professor of Social Studies at that University. He has made important contributions in kinetics and in related branches of physical chemistry, and is the author of a number of books on sociology.] Abstract A further development of London's theory of adiabatic chemical processes, especially atom reactions. The total binding energy of single pairs of atoms is determined from optical data as a function of the interatomic distance and is corrected for the coulombic parts by means of the Heitler–London relation. As examples are taken the linear conversions in the systems The course of a conversion is represented as a motion of a representative point over a surface which represents the binding energy of the atomic system, plotted in space as a function of the interatomic distances.