Question

The decomposition of ozone in the upper atmosphere to dioxygen occurs by a two-step mechanism.The first step is a fast reversible step and the second is a slow reaction between an oxygen atom and an ozone molecule:Step 1: O3(g) O2(g) + O(g) Fast, reversible, reactionStep 2: O3(g) + O(g) → 2O2(g) SlowWhich is the rate determining step?

Answer 1

Answer: Step 2 in the given mechanism is the rate determining step

Explanation:

In a mechanism of the reaction, the slow step in the mechanism determines the rate of the reaction.

The intermediate reaction of the mechanism follows:

Step 1:  $O_3(g)\rightleftharpoons O_2(g)+O(g);\text{ (fast)}$

Step 2:  $O_3(g)+O(g)\rightarrow 2O_2(g);\text{(slow)}$

As, step 2 is the slow step. It is the rate determining step

Rate law for the reaction follows:

$\text{Rate}=k[O_3][O]$

Hence, step 2 in the given mechanism is the rate determining step