Why does a catalyst speed up a reaction?
A catalyst speeds up a reaction by providing an alternative reaction pathway with a lower activation energy.
GCSE Chemistry
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
In more detail
A catalyst gives the reaction a different route to the products that needs less energy to get started (a lower activation energy). This means a greater proportion of the colliding particles now have enough energy to react, so more collisions are successful and the rate increases. The catalyst itself is not used up in the reaction, so a small amount can be reused.
Key points for the exam
- Provides an alternative pathway with lower activation energy.
- More collisions now have enough energy to be successful → faster rate.
- The catalyst is not used up and does not change the products.
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