Kinetics is the study of the rate at which compounds react. This depends on several factors, including the area of contact between the materials, their concentrations, and the temperature at which the reaction takes place. For a reaction k A + m B → C + D, the rate is typically something of the form
- d[C]/dt = k(T)[A]k'[B]m'
- d[C]/dt = ke-Ea/RT[A]k[B]m
For most multi-step reactions the rate is determined primarily by a single slow step, with preceding steps proceeding quickly to a state of rough equilibrium. In general, concentrations of species are never determined solely by a single process, and as reactions occur the products begin to undergo the reverse reaction to some extent. Thus reactions never proceed to 100% completion but rather to a state of chemical equilibrium where every step occurs at the same rate as its reverse.
The Arrhenius equation gives the quantitative basis of the relationship between the activation energy and the rate at which a reaction proceeds.