Equilibrium Treatment of Simultaneous Reactions

The treatment of chemical reaction equilibria outlined above can be generalized to cover the situation where multiple reactions occur simultaneously. In principle one can take all conceivable reactions into account in computing the composition of a gas mixture at equilibrium. However, because of kinetic limitations on the rate of approach of certain reactions to equilibrium, one can treat many systems as if equilibrium is achieved in some reactions but not in others. In many cases, reactions that are thermodynamically possible do not, in fact, occur at appreciable rates. 

In practice, additional simplifications occur because at equilibrium many of the possible reactions either occur 

To arrive at a consistent set of relationships from which complex reaction eqnilibria may be determined, one mnst develop the same nnmber of independent equations as there are nnknowns. The following treatment indicates the Ganss-Jordan method of arriving at a set of chemical reactions that are independent (2). 

If R reactions occur simultaneously within a system composed of S species, one has R stoichiometric eqnations 

Because the same reaction may be written with different stoichiometric coefficients, the importance of the coefficients lies in the fact that the ratios of the coefficients of two species must be identical, no matter how the reaction is written. Thus, the stoichiometric coefficients of a reaction are given only up to a constant multiplier X. The equation s 

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