where the first term alongside the entropic-exponential relation corresponds to the frequency or preexponential factor A. The activation enthalpy ∆ ‡ H at the temperature of interest is included in the last exponential term. For the reactions following second-order kinetics, A should include a pressure-temperature term RT/p °. Finally, the reverse constant rate krev is obtained through the relation between kfwd and K eq for some reversible reactions.