---
title: "Ultraviolet radiation can release \\(\\text{Cl}^{\\boldsymbol{\\cdot}}\\text{(g)}\\) from \\(\\text{CF}_2\\text{Cl}_2\\text{(g)}\\) in the stratosphere. A student examines the following proposed chlorine monoxide dimer cycle. In the mechanism, \\(\\text{M(g)}\\) is an unreactive third-body collision partner, and step \\(1\\) occurs twice for every one occurrence of each other step.  Step \\(1\\): \\[ \\text{Cl}^{\\boldsymbol{\\cdot}}\\text{(g)}+\\text{O}_3\\text{(g)}\\rightarrow\\text{ClO}^{\\boldsymbol{\\cdot}}\\text{(g)}+\\text{O}_2\\text{(g)} \\]  Step \\(2\\): \\[ 2\\,\\text{ClO}^{\\boldsymbol{\\cdot}}\\text{(g)}+\\text{M(g)}\\rightarrow\\text{Cl}_2\\text{O}_2\\text{(g)}+\\text{M(g)} \\]  Step \\(3\\): \\[ \\text{Cl}_2\\text{O}_2\\text{(g)}+h\\nu\\rightarrow\\text{Cl}^{\\boldsymbol{\\cdot}}\\text{(g)}+\\text{ClOO}^{\\boldsymbol{\\cdot}}\\text{(g)} \\]  Step \\(4\\): \\[ \\text{ClOO}^{\\boldsymbol{\\cdot}}\\text{(g)}\\rightarrow\\text{Cl}^{\\boldsymbol{\\cdot}}\\text{(g)}+\\text{O}_2\\text{(g)} \\]  Which choice correctly identifies a catalyst and a reaction intermediate, respectively, in the proposed cycle?"
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url: "https://nerd-notes.com/ubq/120095/"
date_modified: "2026-08-21T08:41:34+00:00"
---

# Ultraviolet radiation can release \(\text{Cl}^{\boldsymbol{\cdot}}\text{(g)}\) from \(\text{CF}_2\text{Cl}_2\text{(g)}\) in the stratosphere. A student examines the following proposed chlorine monoxide dimer cycle. In the mechanism, \(\text{M(g)}\) is an unreactive third-body collision partner, and step \(1\) occurs twice for every one occurrence of each other step.

Step \(1\):
\[
\text{Cl}^{\boldsymbol{\cdot}}\text{(g)}+\text{O}_3\text{(g)}\rightarrow\text{ClO}^{\boldsymbol{\cdot}}\text{(g)}+\text{O}_2\text{(g)}
\]

Step \(2\):
\[
2\,\text{ClO}^{\boldsymbol{\cdot}}\text{(g)}+\text{M(g)}\rightarrow\text{Cl}_2\text{O}_2\text{(g)}+\text{M(g)}
\]

Step \(3\):
\[
\text{Cl}_2\text{O}_2\text{(g)}+h\nu\rightarrow\text{Cl}^{\boldsymbol{\cdot}}\text{(g)}+\text{ClOO}^{\boldsymbol{\cdot}}\text{(g)}
\]

Step \(4\):
\[
\text{ClOO}^{\boldsymbol{\cdot}}\text{(g)}\rightarrow\text{Cl}^{\boldsymbol{\cdot}}\text{(g)}+\text{O}_2\text{(g)}
\]

Which choice correctly identifies a catalyst and a reaction intermediate, respectively, in the proposed cycle?

Ultraviolet radiation can release \(\text{Cl}^{\boldsymbol{\cdot}}\text{(g)}\) from \(\text{CF}_2\text{Cl}_2\text{(g)}\) in the stratosphere. A student examines the following proposed chlorine monoxide dimer cycle. In the mechanism, \(\text{M(g)}\) is an unreactive third-body collision partner, and step \(1\) occurs twice for every one occurrence of each other step.

Step \(1\):
\[
\text{Cl}^{\boldsymbol{\cdot}}\text{(g)}+\text{O}_3\text{(g)}\rightarrow\text{ClO}^{\boldsymbol{\cdot}}\text{(g)}+\text{O}_2\text{(g)}
\]

Step \(2\):
\[
2\,\text{ClO}^{\boldsymbol{\cdot}}\text{(g)}+\text{M(g)}\rightarrow\text{Cl}_2\text{O}_2\text{(g)}+\text{M(g)}
\]

Step \(3\):
\[
\text{Cl}_2\text{O}_2\text{(g)}+h\nu\rightarrow\text{Cl}^{\boldsymbol{\cdot}}\text{(g)}+\text{ClOO}^{\boldsymbol{\cdot}}\text{(g)}
\]

Step \(4\):
\[
\text{ClOO}^{\boldsymbol{\cdot}}\text{(g)}\rightarrow\text{Cl}^{\boldsymbol{\cdot}}\text{(g)}+\text{O}_2\text{(g)}
\]

Which choice correctly identifies a catalyst and a reaction intermediate, respectively, in the proposed cycle?

- **A.** Catalyst: \(\text{O}_3\text{(g)}\); intermediate: \(\text{Cl}_2\text{O}_2\text{(g)}\)
- **B.** Catalyst: \(\text{Cl}^{\boldsymbol{\cdot}}\text{(g)}\); intermediate: \(\text{O}_2\text{(g)}\)
- **C.** Catalyst: \(\text{Cl}^{\boldsymbol{\cdot}}\text{(g)}\); intermediate: \(\text{Cl}_2\text{O}_2\text{(g)}\)
- **D.** Catalyst: \(\text{Cl}_2\text{O}_2\text{(g)}\); intermediate: \(\text{ClO}^{\boldsymbol{\cdot}}\text{(g)}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120095/*