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How do temperature changes affect the rate of a chemical reaction?

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A graph showing a potential energy curve for a chemical reaction, with the y-axis labeled potential energy and the x-axis labeled progress of reaction. The curve rises from the initial state (reactants) to a peak labeled transition state (activated complex), indicating activation energy, then drops to the final state (products). — chemical kinetics In the Arrhenius equation, the activation energy (E) represents the minimum amount of energy required to transform reactants into products in a chemical reaction. On a potential energy curve, the value of the activation energy is equivalent to the difference in potential energy between particles in an intermediate configuration (known as the activated complex, or transition state) and particles of reactants in their initial state. The activation energy thus can be visualized as a barrier that must be overcome by reactants before products can be formed.

In chemical kinetics, temperature is a primary factor influencing the rate of a reaction. As temperature increases, the rate of a chemical reaction typically increases as well.123

This relationship is mathematically described by the Arrhenius equation:

$k = A e^{(- E_{a} / R T)}$

In this expression, k is the reaction-rate constant, A is the pre-exponential factor (related to collision frequency), E_a is the activation energy, R is the universal gas constant, and T is the absolute temperature.45

The increase in reaction rate with temperature is explained by collision theory. For a reaction to occur, molecules must collide with sufficient kinetic energy to overcome the activation energy barrier. While higher temperatures do increase the frequency of molecular collisions, the more significant effect is that a greater fraction of molecules possess enough energy to exceed the activation energy threshold. Consequently, more collisions become effective, leading to a marked increase in the reaction rate.234