Catalysts and Their Action — AQA GCSE Chemistry
Catalysts speed up reactions without being used up, making industrial processes more efficient.
What is a catalyst?
A catalyst is a substance that speeds up a reaction without being used up in the process. At the end of the reaction the catalyst is chemically unchanged, so it can be used again.
How catalysts work
A catalyst works by providing a different reaction pathway with a lower activation energy. This means a greater proportion of collisions are successful, so the rate increases.
On a reaction profile, the catalyst lowers the activation energy "hump" but does not change the energy of the reactants or products (so it doesn't change the overall energy change).
Key points
- Catalysts are specific — a particular catalyst usually only works for a particular reaction.
- Only a small amount of catalyst is needed.
- Catalysts are important in industry because they reduce energy costs and time.
Enzymes
Enzymes are biological catalysts — proteins that catalyse reactions in living organisms and are used in industry (e.g. in making biofuels and in food production).
Exam tips
- A catalyst speeds up a reaction without being used up.
- It works by providing a pathway with a lower activation energy.
- It does not change the amount of product or the overall energy change.
- Enzymes are biological catalysts.