What is the effect of adding a positive catalyst to a chemical reaction at constant temperature?

Answer and explanation

Correct answer: D. Decreases the activation energy without altering

  1. Step 1: A catalyst provides an alternative reaction pathway with a lower activation energy ().
  2. Step 2: Because it accelerates both the forward and reverse reaction rates equally, it has no effect on the enthalpy change () or the equilibrium constant ().
Answer
Decreases the activation energy without altering \Delta H.
Why not the others: 'Increases the activation energy' describes an inhibitor; 'Shifts the equilibrium constant to favor products' is incorrect as catalysts do not alter thermodynamic equilibrium; 'Increases the enthalpy of reaction' is impossible since is a state function.

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