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How do catalysts speed up chemical reactions?
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chemical reaction
Log burning in a fire. Burning wood is an example of a chemical reaction in which wood in the presence of heat and oxygen is transformed into carbon dioxide, water vapor, and ash.
Catalysts accelerate chemical reactions primarily by lowering the activation energy—the minimum amount of energy required for a reaction to occur. By reducing this energy barrier, a catalyst allows a greater number of molecules to undergo chemical transformation under the same conditions.12
The process generally functions through the following mechanisms:
- Formation of Intermediates: The catalyst typically enters into a chemical combination with the reactants to form temporary chemical intermediates. These intermediates are more reactive and can transform into the desired end product more readily than the original reactants.13
- Regeneration: During the final steps of the reaction, the catalyst is regenerated. Because it is not consumed, a single catalyst molecule can facilitate the transformation of many reactant molecules, sometimes at a rate of millions per minute.13
- Reaction Pathways: By providing an alternative reaction pathway with a lower energy requirement, the catalyst increases the overall reaction rate. It is important to note that while catalysts speed up the rate at which equilibrium is reached, they do not change the position of the equilibrium itself.1
In biological systems, these roles are performed by enzymes, which are essential for sustaining life.13