Question

How would you describe the role of the CF₂Cl₂ in the reaction mechanism of Problem 21?

Reference problem-21.Consider the following reaction mechanism:

$$\begin{gathered} {\mathrm{H}}_2{\mathrm{O}}_2\to {\mathrm{H}}_2\mathrm{O}+\mathrm{O} \\ \mathrm{O}+{\mathrm{CF}}_2{\mathrm{Cl}}_2\to \mathrm{ClO}+{\mathrm{CF}}_2\mathrm{Cl} \\ \mathrm{ClO}+{\mathrm{O}}_3\to \mathrm{Cl}+2{\mathrm{O}}_2 \\ \mathrm{Cl}+{\mathrm{CF}}_2\mathrm{Cl}\to {\mathrm{CF}}_2{\mathrm{Cl}}_2 \end{gathered}$$

(a) What is the molecularity of each elementary step?

(b) Write the overall equation for the reaction.

(c) Identify the reaction intermediate(s)

Short answer

CF₂Cl₂ acts as a catalyst

Step-by-step solution

Mechanism

$$\begin{gathered} {\mathrm{H}}_2{\mathrm{O}}_2\to {\mathrm{H}}_2\mathrm{O}+\mathrm{O} \\ \mathrm{O}+{\mathrm{CF}}_2{\mathrm{Cl}}_2\to \mathrm{ClO}+{\mathrm{CF}}_2\mathrm{Cl} \\ \mathrm{ClO}+{\mathrm{O}}_3\to \mathrm{Cl}+2{\mathrm{O}}_2 \\ \mathrm{Cl}+{\mathrm{CF}}_2\mathrm{Cl}\to {\mathrm{CF}}_2{\mathrm{Cl}}_2 \end{gathered}$$

In the above mechanism, CF₂Cl₂ participates in the reaction and it undergoes peramanent change to give products. CF₂Cl₂ acts as catalyst and affects the rate of the reaction corresponding to ozone decomposition.

CF₂Cl₂ affects the rate law corresponding to O₃ decomposition reaction by providing new pathways, by which new reaction occurs.