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CBSE Class 12 · 2017 · Chemical KineticsVery Short Answer

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What is the effect of adding a catalyst on
(a) activation energy (E), and
(b) Gibbs energy (ΔG) of a reaction?

Answer: (a) E_a decreases (alternative lower-energy path). (b) ΔG is unchanged.

Solution

(a) A catalyst provides an alternative path of lower activation energy, so decreases — more molecules can cross the barrier and the rate rises.
(b) A catalyst has no effect on (or on , or the equilibrium constant) — the thermodynamics of the reaction is unchanged; only the speed of attaining equilibrium increases.

CBSE Class 12 Board · 2017 · Subjective

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