Multiple Reactions in a Single-Phase System

Consider a homogeneous closed system made initially of. .. 

The total Gibbs free energy of the system at equilibrium is  

Introduction of Eq. 12.6.7 into Eq. 12.3.9, combined with the Gibbs-Duhem equation, yields  

In order that Eq. 12.6.9 be satisfied for arbitrary changes in all independent variables, Cj, 2. 

Thus when a single-phase system, where multiple reactions take place, reaches equilibrium, so does each of the reactions involved. 

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