Global distribution 263 Diffusion equation

The dissociation of a molecule in solution and the approach to an equilibrium distribution of molecules and radicals has been treated by Berg [278]. His detailed and careful analysis uses the diffusion equation exclusively to describe microscopic motion. During molecular dissociation on a microscopic scale (i.e. involving only a few molecules), molecules dissociate, recombine, dissociate etc. many times. The global rate of dissociation is much less than that of an individual molecule, indeed smaller by a factor of (1 + kACijAiiRD), that is an average number of times the molecule dissociates and recombines. For reactions which do not go to completion... 

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