Definition of energy of activation

1) An operationally defined quantity expressing the dependence of a rate constant on temperature according to

Ea = RT2([partial differential] ln k /[partial differential]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.