Introduction to Kinetic Measurements

Another requirement for successful measurement of heterogeneous kinetics is that R must be at least comparable to Z , i.e., the overall process must not be diffusion controlled. 

When the ET rate is much slower than that of the mass transfer, the process is practically irreversible, and the determination of the kinetic parameters is relatively straightforward (see Section 2.1.1 in reference (1) for the discussion of electrochemical reversibility). In contrast, when the mass transfer and ET rates are comparable, the process is quasi-reversible and the kinetic analysis is more complicated. 

The mass transfer rate can be expressed in terms of the mass transfer coefficient m. For uniformly accessible electrodes, the mass transfer coefficient can be defined as 

The kinetic parameters of a coupled homogeneous chonical reaction can be determined elecIrochemicaUy as long as they affect the magnitude of the measured signal. Because of the huge variety of possible multi-step processes, it is not easy to define the limits of measurable 

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