Preliminary Aspects of Thermodynamics and Kinetics

AG is the energy difference between the reactants and products, and since the reaction is spontaneous AG must have a negative value. Note that AG is the energy barrier that A and B have to surmount to give products C and D. This arises from the internal energy of A and B. Once the activated complex (A B) is formed is can revert to A and B or give C and D, and the latter is energetically favoured because the reaction under 

When k( kb we have a large value for K and the forward reaction is predominant and the reverse reaction is negligible. On the other hand when kf kb the reverse reaction is favoured and the value of K is very small. 

For the forward reaction the temperature dependence is given by the Arrhenius equation. 

For the reverse reaction (i.e., conversion of C and D into A and B), the activation energy required will be greater than AG, and the reverse reaction is not favored. 

From thermodynamics we have the relationship between free energy and equilibrium constant for a reaction  

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