Question

it is known that compounds called chlorofluorocarbons (cfcs) e.g. cfcl₃ will break up in the presence of ultraviolet radiation, such as in the upper atmosphere, forming single chlorine atoms: cfcl₃ → cfcl₃ + cl the cl atoms then react with ozone (o₃) as outlined in the following mechanism: step 1: cl + o₃ → clo + o₂ step 2: clo + o → cl + o₂ (single \o\ atoms occur naturally in the atmosphere) 1) write the equation for the overall reaction. use the following format: a a + b b → c c + d d your answer

Explanation:

Step1: List all reactions

We have three reactions:

1. \( CFCl_3

ightarrow CFCl_2 + Cl \)

1. \( Cl + O_3

ightarrow ClO + O_2 \)

1. \( ClO + O

ightarrow Cl + O_2 \)

Step2: Add all reactions together

Add the left - hand sides (LHS) and right - hand sides (RHS) of the three reactions:

LHS: \( CFCl_3+Cl + O_3+ClO + O \)

RHS: \( CFCl_2 + Cl+ClO + O_2+Cl + O_2 \)

Step3: Cancel out intermediate species

The intermediate species are \( Cl \) and \( ClO \) (they appear on both LHS and RHS). After canceling them:

LHS: \( CFCl_3+O_3 + O \)

RHS: \( CFCl_2+O_2+O_2 \)

Simplify the RHS: \( CFCl_2 + 2O_2 \)

But we can also consider the reaction of ozone and oxygen atom with the help of the catalytic action of Cl. If we ignore the \( CFCl_3 \) decomposition for the overall reaction of ozone depletion (since the question might be focused on the ozone - related overall reaction from the two - step mechanism of Cl with ozone and O), let's re - evaluate.

From the two - step mechanism (step 2 and step 3, considering the Cl from step 1 as a catalyst):

Step 2: \( Cl + O_3
ightarrow ClO + O_2 \)

Step 3: \( ClO + O
ightarrow Cl + O_2 \)

Adding these two:

LHS: \( Cl + O_3+ClO + O \)

RHS: \( ClO + O_2+Cl + O_2 \)

Cancel \( Cl \) and \( ClO \):

We get \( O_3+O
ightarrow 2O_2 \)

Answer:

\( O_3 + O
ightarrow 2O_2 \) (or if we include the \( CFCl_3 \) decomposition, but the main ozone - related overall reaction from the Cl - catalyzed steps is \( O_3+O
ightarrow 2O_2 \))