In almost all cases, increasing the temperature of a reaction increases the kinetic energy of the molecules and thus makes them collide more frequently. An increase of 10 Kelvins approximately doubles the reaction rate. Since the reaction rate is changing, the rate constant must also change. The rate constant changes according to the Arrhenius equation:
In equation (1), k is the rate constant, R is the gas constant, T is temperature in K, and A is the preexponential factor proportional to the collision frequency. Ea is the activation energy of the reaction being examined.
In order for a product to form, energy must be injected into the system to overcome the activation energy barrier that exists between reactants and products. When this activation energy is provided, the transition state forms and then decomposes to form the products. If the mechanism for a reaction has several steps, there is a separate activation energy and transition state associated with each step.
The Arrhenius equation is a numerical representation of the fact that the rate of a reaction is directly proportional to the activation energy of the reaction.
