Diagnostic Criteria to Identify an Irreversible Process

1 Diagnostic Criteria to Identify an Irreversible Process. In order to characterize an irreversible process it would be necessary to be able to calculate either the thermodynamic parameter E° or the kinetic parameters a. and k°. Unfortunately, we will see below that k° can only be calculated if E0/ is known, and E0 cannot be calculated by voltammetric techniques. Thus, either one knows Eel (for example, by using potentiometric techniques in solutions containing both Ox and Red), or one is limited to give simply the peak potential of the electrode process at a certain rate (usually at 0.1 V s-1 or at 0.2 V s-1). 

At 25°C, the shift is of about 30/oina mV for a tenfold increase of the scan rate. 

Such a relationship is commonly employed to calculate the term a na. 

The precise dependence of Ep with scan rate v is expressed by  

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