Catalysts

This lesson covers catalysts, how they work using collision theory, the concept of activation energy, biological catalysts (enzymes) and the economic importance of catalysts as required by the Edexcel GCSE Combined Science specification (1SC0).

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What Is a Catalyst?

A catalyst is a substance that increases the rate of a chemical reaction without being used up or chemically changed at the end of the reaction.

Key Features

Feature	Explanation
Increases rate	The reaction proceeds faster with a catalyst present
Not used up	The catalyst is the same mass and chemical composition before and after the reaction
Provides an alternative pathway	The catalyst offers a different route for the reaction that has a lower activation energy
Specific	Most catalysts only work for particular reactions
Small amount needed	A catalyst is not a reactant — it is not included in the balanced equation

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How Do Catalysts Work?