Definition of pre-exponential factor

See energy of activation, entropy of activation.

energy of activation: An operationally defined quantity expressing the dependence of a rate constant on temperature according to

Ea = RT2( ln k /T)p

as derived from the "Arrhenius equation", k = A exp(-Ea/RT), where A (SI unit: as for the corresponding rate constant) is termed the "pre-exponential factor". See also enthalpy of activation.