Theorem of the concentrations in pure mode

We will first state and check a very important theorem, which connects the concentrations of the intermediate species to those of the main components of the reaction (reactant and products). 

Theorem.- In a pure mode, all the intermediate species are in equilibrium with reactants and/or products of the reaction, and consequently the concentrations of the intermediate species are connected to concentrations of reactants and/or products. 

We cannot give a general demonstration of this theorem because there is no general linear mechanism. We will check it on a simple linear mechanism and also in the case of om example of the oxidation of magnesium. 

Take again the simple mechanism made up of the reactions [7.Et.bl] to [7.Et.bn-i-1], 

We will reason using the rate factors f p of stage p from left to right and fp from right to left. We know that rate factor fp is constant if we work at a constant temperatme and with constant concentrations of the main reactants and products. 

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