CHEMISTRY · Single correct · A Level · Chemistry · Kinetics · Kinetics
Problem
For a particular reaction at 298 K, the uncatalyzed pathway has Ea=120kJmol−1 and ΔG∘=−30kJmol−1. A catalyst provides an alternative pathway with Ea=60kJmol−1 while leaving ΔG∘ unchanged.
Which option best explains how the catalyst alters the reaction profile?
(a) It lowers both Ea and ΔG∘, making the reaction more spontaneous and faster.
(b) It lowers only the forward activation energy, so the reverse barrier remains high and the equilibrium shifts strongly toward products.
(c) It lowers the energy barrier, increasing the rate so the thermodynamically favored reaction can take place without altering the position of equilibrium.
(d) It increases the temperature of the reacting mixture, which according to the Arrhenius equation effectively reduces Ea and speeds up the reaction.