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O Levels Chemistry (5070)•5070/12/M/J/20
Question 18 from 5070/12/M/J/20

Explanation

Catalysts Reduce Activation Energy in Reactions

Steps:

  • Define activation energy as the minimum energy barrier for reactants to form products.
  • Recall that reaction rate depends on factors like collision frequency and activation energy.
  • Evaluate each option: only catalysts directly alter the energy pathway.
  • Confirm that lowering activation energy speeds up the reaction without changing other conditions.

Why A is correct:

  • Catalysts provide an alternative reaction pathway with lower activation energy, increasing the rate constant per the Arrhenius equation (k = A e^(-Ea/RT)).

Why the others are wrong:

  • B: Increases surface area boosts collision frequency between particles, not activation energy.
  • C: Raises acid concentration increases reactant collisions, without affecting activation energy.
  • D: Elevates temperature gives particles more kinetic energy to surpass the activation energy barrier, but does not lower it.

Final answer: A

Topic: Rate of reaction

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