Catalysts are used in chemical reactions to accelerate the reaction without being used up in the reaction. They work by lowering the amount of energy needed to start a chemical reaction. The image below shows that the activation energy (Ea, the minimum energy required for a chemical reaction to occur) with the catalyst is reduced. This is usually achieved by the reaction following a different reaction pathway.
An example of catalysts are the metals platinum and rhodium in catalytic converters in cars. The catalytic converter accelerates the reaction between carbon monoxide and unburnt fuel to produce carbon dioxide and water, which are less harmful to the environment than the starting materials.
Catalysts can also be used for selectivity. They can direct a reaction to produce a desired product. The use of different catalysts can thus direct the reaction to different products. For example, using a nickel catalyst in the reaction between hydrogen and carbon monoxide gives methane and water as products while using a copper catalyst gives formaldehyde as the product.
Compiled by Lucy Bird.