Problem 21 - Chemistry The Central Science

Question

Do the reactions involved in ozone depletion involve changes in oxidation state of the O atoms? Explain.

Step-by-Step Solution

Answer

In the reactions involved in ozone depletion, there are changes in the oxidation state of the O atoms, specifically in the chlorine-catalyzed ozone destruction reactions. In these reactions, the oxidation state of the O atoms changes from 0 to -2, and then back to 0. However, there is no change in the oxidation state of O atoms in the ozone formation and decomposition reactions.

Step 1: Identify the reactions involved in ozone depletion

The main reactions involved in ozone depletion are the ozone formation and decomposition reactions and chlorine-catalyzed ozone destruction reactions. Ozone formation and decomposition reactions: 1. \( O_2 + O \xrightarrow{Sunlight} O_3 \) 2. \( O_3 + O \xrightarrow{Sunlight} 2O_2 \) Chlorine-catalyzed ozone destruction reactions: 1. \( Cl + O_3 \rightarrow ClO + O_2 \) 2. \( ClO + O \rightarrow Cl + O_2 \)

Step 2: Examine the oxidation states of O atoms

To determine if there are any changes in the oxidation state of the O atoms, let's examine the oxidation states of oxygen in each reaction. Oxidation states: 1. In diatomic oxygen (\( O_2 \)), the oxidation state of an O atom is 0. 2. In ozone (\( O_3 \)), the oxidation state of each O atom in the molecule is 0. 3. In a single O atom, the oxidation state is 0. 4. In the chlorate ion (\( ClO^- \)), the oxidation state of O is -2. Reviewing the reactions: Ozone formations and decomposition reactions: 1. \( O_2 + O \xrightarrow{Sunlight} O_3 \) 0 + 0 → 0 2. \( O_3 + O \xrightarrow{Sunlight} 2O_2 \) 0 + 0 → 0 + 0 Chlorine-catalyzed ozone destruction reactions: 1. \( Cl + O_3 \rightarrow ClO + O_2 \) 0 → -2 + 0 2. \( ClO + O \rightarrow Cl + O_2 \) -2 + 0 → 0 + 0

Step 3: Determine if changes in oxidation state occur

Based on our examination of the oxidation states, we can see that for the ozone formation and decomposition reactions, there is no change in the oxidation state of the O atoms. However, in the chlorine-catalyzed ozone destruction reactions, there is a change in the oxidation state of the O atoms from 0 to -2 and back to 0. Therefore, ozone depletion does involve changes in the oxidation state of the O atoms, particularly in the chlorine-catalyzed ozone destruction reactions.