Chemistry

The key is to recognize that the rate-determining step (the slow one) controls the overall reaction rate, and only reactants present in that step—or intermediates formed before it—appear in the rate law. Here, Step 1 is slow and consumes $\text{O}_3$ and $\text{Cl}$ directly, giving rate = $k[\text{O}_3][\text{Cl}]$. The fast Step 2 then consumes the intermediate $\text{ClO}$ and doesn't affect the rate law. Since the proposed mechanism's rate-determining step matches the experimental rate law exactly, the mechanism is consistent.

The key is to recognize that the rate-determining step (the slow one) controls the overall reaction rate, and only reactants present in that step—or intermediates formed before it—appear in the rate law. Here, Step 1 is slow and consumes $\text{O}_3$ and $\text{Cl}$ directly, giving rate = $k[\text{O}_3][\text{Cl}]$. The fast Step 2 then consumes the intermediate $\text{ClO}$ and doesn't affect the rate law. Since the proposed mechanism's rate-determining step matches the experimental rate law exactly, the mechanism is consistent.