A student investigating the exothermic equilibrium adds a catalyst at constant…
CHEMISTRY · Single correct · A Level · Chemistry · Kinetics · Kinetics
Problem
A student investigating the exothermic equilibrium SO2Cl2(g)⇌SO2(g)+Cl2(g)(ΔH∘<0) adds a catalyst at constant temperature and pressure. The student predicts that the catalyst will shift the equilibrium toward the reactant side because the reverse reaction has the larger activation energy.
Which of the following evaluations of the student’s prediction is most accurate?
(a) Incorrect, because catalysts affect only endothermic reactions and have no influence on exothermic equilibria.
(b) Incorrect, because a catalyst lowers the activation energy of both directions equally and therefore does not change the equilibrium position.
(c) Correct, because decreasing the activation barrier lowers the overall enthalpy change, reversing the sign of ΔH∘ and shifting the equilibrium.
(d) Correct, because lowering the higher activation energy of the reverse reaction makes that direction faster and forces the equilibrium to favor reactants.