Transition State Theory

The transition state theory is also known as the activated-complex theory. It explains the rates of reaction in both solution and gas phases, such as precipitation in solution and ammonia synthesis in gases.

As two reactants approach each other, their potential energy increases and ultimately reaches a maximum, as depicted by the reaction profile.

This maximum point represents the potential energy barrier that the reactants must overcome to initiate the reaction.

The activated complex refers to the collection of species near the transition state, while the transition state here represents the single highest-energy configuration at the peak of the energy barrier.

From this point, the transition state can either collapse back into the reactants or decay into products.

In bimolecular reactions, the reaction rate is described using the Eyring equation. It links the rate constant to the transmission coefficient, Boltzmann’s constant, temperature, the transition-state equilibrium constant, the standard concentration, and Planck’s constant.

The equilibrium constant is related to the Gibbs free energy of activation, so it can also be written in terms of ΔG.