The Statistical Nature of Chemical Changes

If the world reached equilibrium it would be a sterile and ungracious place winds and rivers would become quiescent, fires burnt out, and life extinct. All the events which give vitality and movement to the scene are transitions towards equilibrium from the condition of violent unbalance in which the universe was found at the beginning of the present cosmological era—whenever and whatever that incomprehensible point of departure was. 

The routes to equilibrium are manifold and tortuous, and the theory of the processes of change more complicated than that of equilibria themselves. Apart from a passing consideration of nuclear changes we shall be concerned only with chemical reactions in the ordinary sense of the term. 

At the outset the principles which govern the rate of establishment of equilibrium were by no means easy to discern. Obviously much of the matter in the world is separated by large distances from other matter with which it might react and evaporation, solution, and diffusion are the factors which limit the occurrence of many possible changes. But there is a real chemical inertia of some kind which slows down, often to a negligible speed, the reactions even of substances perfectly mixed in the gaseous state. 

There arises naturally enough the question whether the rate of a given transformation should not be a function of its free energy, and indeed the equation  

This law is expressed, with good approximation, by the equation 

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