How Does the Gibbs Free Energy Evolve in a System Undergoing Coupled Competitive Reactions?

The kinetic and thermodynamic behavior of a chemical system undergoing coupled competitive reactions is analyzed. It is illustrated by considering the hydrogenation reaction of a Vaska type complex. In a first part, the meaning of kinetic/thermodynamic controls and of kinetic stability is thoroughly revisited. The different regimes are defined by reference to the characteristic times emerging from equations describing the evolution. In a second part, it is shown how the Gibbs free energy of the reacting system varies when successively submitted to kinetic and thermodynamic controls.