Pole diagrams of two reactions in the same family

It is often interesting to use the same system of axes to plot the pole diagrams of two reactions involving similar systems. We shall now examine two examples. 

Let us first look at the reactions of reduction of the same metal oxide MO, by hydrogen on the one hand, and by carbon monoxide on the other. 

At the same temperature, each of the reactions is represented by a pole -P and P respectively. In the same way as in the previous section, we can 

This is the temperature for which, at equilibrium, we have the relation  

Similarly, let us now compare the pole diagrams of reduction of two metal oxides, MO and M O by hydrogen, as follows  

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