Coupled homogeneous chemical reaction table

Chapter 12. Electrode Reactions with Coupled Homogeneous Chemical Reactions TABLE 12.1.1 Approximate Time Windows for Different Electrochemical Techniques... 

The coupling of fast electron transfer with homogeneous chemical reaction requires the combination of chemical reaction rate term (see Table 1) with material fluxes evoked by the production/consumption of electroactive species and products during the current flow. The mathematical solution (numerical integration of differential equations) results in relations that seem to be rather confused for electrochemical practice. 

Let us first consider briefly how the use of mass transport as a variable can provide a guide to the reaction mechanism and give quantitative kinetic detail. As an illustration, we consider the behaviour of CE and EC processes (where E signifies electron transfer and C represents a chemical step) at a rotating disc electrode (RDE). This hydrodynamic system has already been discussed by Albery et al. and the reader is referred to Chap. 4 for details. CE and EC processes represent the simplest conceivable electrode reactions involving coupled homogeneous kinetics mechanistic examples of both types are shown in Table 1. In the discussion which follows, the electron-transfer reaction in the two mechanisms is considered to be a cathodic process the extension to the anodic case is trivial. 

Table 2.5 hsts homogeneous as well as heterogeneous redox couples. In heterogeneous couples, in the course of a redox reaction, electrons cross a phase boimdary. As a result, electric quantities like potential or current are directly related to chemical quantities. They can be measured easily by electrochemical methods, since electrochemistry deals with charge transfer processes. Consequently, the group of electrochemical sensors is one of the most important groups of chemical sensors. 

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