For a bimolecular reaction, e.g. A + B → AB, the speed of reaction, i.e. chemical kinetics, is expressed as the rate of reaction R = k[A] [B], the product of a rate constant k times the concentrations of A and B in the mixture. The reaction rate constant can be predicted by the Arrhenius equation, 𝑘 = 𝑍𝑒 -𝐸 𝑎 𝑘 𝐵 𝑇 (1) where Z is the collision frequency between A and B in a unit volume with unit concentrations of A and B, Ea is the activation energy, kB is the Boltzmann constant, and T is the temperature in the Kelvin scale. The exponential part of the equation is a function of temperature representing the fraction of reactive collisions in all the collisions. This fraction is in the exponential term that is derived from the error function of the Maxwell-Boltzmann energy distribution (a theory started by Maxwell around the 1860s and generalized by Boltzmann around the 1870s) of these molecules that have larger than a threshold activation energy. The problem left by Maxwell, Boltzmann, and Arrhenius to predict a reaction rate is how to calculate the collision frequency and the activation energy of the reaction.