Eyring equation

The Eyring equation (occasionally also known as Eyring–Polanyi equation) is an equation used in chemical kinetics to describe the variance of the rate of a chemical reaction with temperature. It was developed almost simultaneously in 1935 by Henry Eyring, Meredith Gwynne Evans and Michael Polanyi. This equation follows from the transition state theory (a.k.a. activated-complex theory) and (if one assumes constant enthalpy of activation and constant entropy of activation) is similar to the empirical Arrhenius equation, although the Arrhenius equation is empirical, and the Eyring equation has a statistical mechanical justification. The Eyring equation (occasionally also known as Eyring–Polanyi equation) is an equation used in chemical kinetics to describe the variance of the rate of a chemical reaction with temperature. It was developed almost simultaneously in 1935 by Henry Eyring, Meredith Gwynne Evans and Michael Polanyi. This equation follows from the transition state theory (a.k.a. activated-complex theory) and (if one assumes constant enthalpy of activation and constant entropy of activation) is similar to the empirical Arrhenius equation, although the Arrhenius equation is empirical, and the Eyring equation has a statistical mechanical justification. The general form of the Eyring–Polanyi equation somewhat resembles the Arrhenius equation:   k = κ k B T h e − Δ ‡ G ⊖ R T {displaystyle k={frac {kappa k_{mathrm {B} }T}{h}}mathrm {e} ^{-{frac {Delta ^{ddagger }G^{ominus }}{RT}}}} where ΔG‡ is the Gibbs energy of activation, κ is the transmission coefficient, kB is Boltzmann's constant, and h is Planck's constant. The transmission coefficient is often assumed to be equal to one as it reflects what fraction of the flux through the transition state proceeds to the product without recrossing the transition state, so a transmission coefficient equal to one means that the fundamental no-recrossing assumption of transition state theory holds perfectly.