Transition State Theory
The theory that treats the activated complex as being in quasi-equilibrium with reactants and calculates rate from its decomposition frequency.
Formula / equation
k = (k_BT/h) e^(−ΔG‡/RT)
Unit
Various
In depth
Also called absolute rate theory, it expresses the barrier in thermodynamic terms as an enthalpy and entropy of activation. The entropy term explains why reactions that require a highly ordered transition state are slow even when the energy barrier is modest.
Examples in the real world
A cyclisation with a strongly negative ΔS‡ is slow because the reacting ends must find each other precisely.