Transport, Transfer and Reaction

In spite of the complexity of real processes most cases of interest may be effectively described by a heterogeneous pseudo-monomolecular reaction of the type 

In both cases we are not specifically dealing with reorganization processes which are more complicated than in the case of liquids and specifically related with the crystal structure.176 177 More precisely the first special case is met, if, for reactions, the difference in the space coordinate does not matter (i.e., if zA x) = zB x )). Hence pure gas phase reactions or neutral surface reactions can be described by Eq. (93), while Eq. (94) refers to pure transport steps (transport within the same structure). The description of typical electrochemical reactions such as charge transfer reactions require the analysis ofEq. (92). (We will see later that mechanistic equations are typically bimolecular, however, owing to the constancy of regular constituents, the consideration ofEq. (92) suffices in most cases of interest.) 

Two approaches will be considered one is to apply linear irreversible thermodynamics according to which the generalized rate 

5R depends linearly on the generalized driving force A (corresponding 

In a better approximation SR (of process k) can also depend on secondary driving forces such that 

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