Thermodynamics and Chemical Equilibrium

This relation is credited to Svante Arrhenius and is called the Arrhenius temperature dependence. Arrhenius was mainly concerned with thermodynamics and chemical equilibrium. Some time later Michael Polanyi and Eugene Wigner showed that simple molecular arguments lead to this temperature dependence, and this form of the rate is frequently called the Polanyi-Wigner relation. They described chemical reactions as the process of crossing a potential energy surface between reactants and products (see Figure 2-3), where f and... 

A rational deduction of elemental abundance from solar and stellar spectra had to be based on quantum theory, and the necessary foundation was laid with the Indian physicist Meghnad Saha s theory of 1920. Saha, who as part of his postdoctoral work had stayed with Nernst in Berlin, combined Bohr s quantum theory of atoms with statistical thermodynamics and chemical equilibrium theory. Making an analogy between the thermal dissociation of molecules and the ionization of atoms, he carried the van t Hoff-Nernst theory of reaction-isochores over from the laboratory to the stars. Although his work clearly belonged to astrophysics, and not chemistry, it relied heavily on theoretical methods introduced by and associated with physical chemistry. This influence from physical chemistry, and probably from his stay with Nernst, is clear from his 1920 paper where he described ionization as a sort of chemical reaction, in which we have to substitute ionization for chemical decomposition. [81] The influence was even more evident in a second paper of 1922 where he extended his analysis. [82]... 

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