Finely divided powder is commonly used to catalyze the hydrogenation of alkenes in…
CHEMISTRY · Single correct · A Level · Chemistry · Kinetics · Kinetics
Problem
Finely divided Ni powder is commonly used to catalyze the hydrogenation of alkenes in the liquid phase. Which of the following statements best explains how the nickel catalyst increases the rate of this reaction?
(a) Nickel increases the temperature of the reaction mixture through heat released upon adsorption, leading to faster molecular collisions.
(b) Nickel dissolves hydrogen within its lattice, increasing the effective concentration of H2 in the solution and shifting the equilibrium toward products.
(c) Hydrogen and alkene molecules are weakly adsorbed onto the nickel surface, allowing bonds to break and reform through surface-bound intermediates that require less energy.
(d) A transient nickel hydride species forms in solution and directly transfers a hydride ion to the alkene, avoiding the high-energy surface reaction pathway.