Question

step 1: o₃(g) + cl(g) → o₂(g) + clo(g) step 2: clo(g) + o(g) → o₂(g) + cl(g) a proposed mechanism for the destruction of o₃(g) in the upper atmosphere is represented above. which of the following is the catalyst in the proposed mechanism? a o(g) b cl(g) c clo(g) d o₂(g)

Explanation:

A catalyst is a substance that increases the rate of a reaction without being consumed in the overall reaction. Let's analyze the two steps:

• Step 1: $\ce{O3(g) + Cl(g) -> O2(g) + ClO(g)}$
• Step 2: $\ce{ClO(g) + O(g) -> O2(g) + Cl(g)}$

When we add these two steps together (to get the overall reaction), we can see that $\ce{Cl(g)}$ is a reactant in Step 1 and a product in Step 2. This means it is regenerated and not consumed in the overall reaction.

• $\ce{O(g)}$ is a reactant in Step 2 and not present initially as a reactant to be regenerated.
• $\ce{ClO(g)}$ is a product in Step 1 and a reactant in Step 2, so it's an intermediate (consumed in the overall reaction).
• $\ce{O2(g)}$ is a product in both steps, so it's a product of the reaction, not a catalyst.

So, $\ce{Cl(g)}$ (option B) acts as the catalyst as it speeds up the reaction (by providing an alternative mechanism) and is regenerated.

Answer:

B. $\ce{Cl(g)}$