Page "Arrhenius equation" Paragraph 29

At first sight this looks like an exponential multiplied by a factor that is linear in temperature.

However, one must remember that free energy is itself a temperature dependent quantity.

The free energy of activation is the difference of an enthalpy term and an entropy term multiplied by the absolute temperature.

When all of the details are worked out one ends up with an expression that again takes the form of an Arrhenius exponential multiplied by a slowly varying function of T. The precise form of the temperature dependence depends upon the reaction, and can be calculated using formulas from statistical mechanics involving the partition functions of the reactants and of the activated complex.