Catalysts Practice Test

The reaction $2\text{NO}(g)+\text{O}_2(g)\rightarrow 2\text{NO}_2(g)$ is run at the same temperature and initial pressures in two containers. In Container 2, a catalyst is present and is recovered unchanged; the overall reactants and products are the same.

Which statement best explains why the reaction rate is higher in Container 2?

Nitrogen monoxide reacts with ozone in the gas phase: $\text{NO}(g)+\text{O}_3(g)\rightarrow \text{NO}_2(g)+\text{O}_2(g)$. A second run is performed with a small amount of $\text{Cl}(g)$ present as a catalyst; the overall reactants and products are the same in both runs, and $\text{Cl}(g)$ is not consumed.

Which statement best explains why the catalyzed run has a higher reaction rate?