Electron Potential, pe

The concept of electron potential was introduced as an analogy between p, which refers to hydrated protons, and pe, which would refer to hydrated electrons. Like pW, pe is defined in terms of activity  

In fact the p notation is now widely used for various quantities. For example, equilibrium constants are sometimes given in terms of pK, where 

There are no hydrated electrons in real solutions, just as there may be no oxygen. However, this does not detract from the usefulness of pe or of log fo2 as indices of redox conditions. They are calculated numbers, based on actual voltages or concentrations. 

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The electron potential pe is an alternative expression of electron availability. From Eq. 4.19,... 

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