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How does a catalyst lower the activation energy of a chemical reaction?

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dissociation of E–N — reaction mechanism Possible energy diagram for the dissociation of a covalent molecule, E–N, into its ions E⁺ and N⁻ (see text).

A catalyst lowers the activation energy of a chemical reaction by providing an alternative reaction pathway or mechanism that is more energetically favorable than the uncatalyzed route.1

In this process, the catalyst generally enters into a chemical combination with the reactants to form an intermediate stage. By participating in the formation of these intermediates, the catalyst allows the reaction to proceed through steps that require less energy than the original, uncatalyzed transformation. Because the catalyst is not consumed in the reaction, it is ultimately regenerated, allowing a single catalyst molecule to facilitate the transformation of many reactant molecules.12

It is important to note that while a catalyst accelerates the rate at which a reaction reaches equilibrium, it does not change the position of that equilibrium, as it accelerates both the forward and reverse reactions equally.1