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How a catalyst increases reaction speed

Short answer

A catalyst increases reaction speed by providing a new reaction path with lower activation energy. At a given temperature, more molecules have sufficient energy to overcome this lower barrier, so the number of effective collisions and the rate constant increase.

Give an account how a catalyst increases the speed of a reaction.

A catalyst provides a new reaction path with a lower activation energy (Ea). More reacting molecules then have energy equal to or greater than the lowered threshold at the same temperature, so the number of effective collisions rises and the reaction becomes faster (rate constant k = A e^(−Ea/RT) increases). The catalyst is regenerated at the end.

Activation energy on the path R → P

  uncatalysed : ████████████  (high Ea)
  catalysed   : ████          (low Ea)

  Catalyst lowers the barrier; R and P levels unchanged.

The energies of reactants (R) and products (P) are unchanged, so ΔH is the same; only the barrier is lowered.

✓ Answer checked by Claude Opus 5.5 (high effort)

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