Example Calculation, pe-pH

Because all pe-pH calculations are similar, we will only use one example to illustrate the general method. 

In the above section on Eh, we showed that the boundary Mn(0H)2 Mn304 can be described by the equation 

This could be used to calculate an equation for the same boundary in the variables pe and pH from relationship (18.44)  

Substituting (18.44) into (18.24) does reproduce the pe-pH equation (18.45) exactly, showing that the two variables Eh and pe are interchangeable for practical purposes and you can choose whichever you prefer to calculate redox boundaries. 

In the above treatment of the variable pe, we began with the definition 

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