Question

Which one of the following statements is not correct?

• A. Chlorine oxidises ferrous salts to ferric salts in acidic medium
• B. Chlorine oxidises iodine to periodic acid in water
• C. Chlorine acts as a bleaching agent due to oxidation
• D. Chlorine is manufactured by Deacon's process

Hint:

When dealing with redox reactions of halogens, remember the trend of oxidizing power: F₂>Cl₂>Br₂>I₂. A halogen can oxidize the halide ions below it in the group. Chlorine can oxidize Br⁻ and I⁻, but the extent of oxidation of iodine to oxoacids is usually up to the +5 state (iodic acid), not the +7 state.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
This question tests the knowledge of the chemical properties of chlorine (Cl₂), particularly its role as an oxidizing agent, a bleaching agent, and its industrial preparation.
Step 2: Analyzing Each Statement:
- (A) Chlorine oxidises ferrous salts to ferric salts in acidic medium: This is correct. Chlorine is a strong oxidizing agent. It can oxidize iron(II) to iron(III).
\[ 2\text{Fe}^{2+}(aq) + \text{Cl}_2(g) \rightarrow 2\text{Fe}^{3+}(aq) + 2\text{Cl}^-(aq) \] - (B) Chlorine oxidises iodine to periodic acid in water: This is incorrect. Chlorine in the presence of water does oxidize iodine, but it oxidizes it to iodic acid (HIO₃), not periodic acid (HIO₄).
\[ \text{I}_2 + 5\text{Cl}_2 + 6\text{H}_2\text{O} \rightarrow 2\text{HIO}_3 + 10\text{HCl} \] Periodic acid has iodine in the +7 oxidation state, while iodic acid has iodine in the +5 oxidation state. Chlorine is not a strong enough oxidizing agent under these conditions to oxidize iodine to the +7 state.
- (C) Chlorine acts as a bleaching agent due to oxidation: This is correct. In the presence of moisture, chlorine produces nascent oxygen, which is a powerful oxidizing agent and is responsible for the bleaching action.
\[ \text{Cl}_2 + \text{H}_2\text{O} \rightarrow \text{HCl} + \text{HOCl} \] \[ \text{HOCl} \rightarrow \text{HCl} + [O] \] Colored substance + [O] \(\rightarrow\) Colorless oxidized substance.
- (D) Chlorine is manufactured by Deacon's process: This is correct. The Deacon's process is a major industrial method for producing chlorine by the catalytic oxidation of hydrogen chloride gas.
\[ 4\text{HCl} + \text{O}_2 \xrightarrow{\text{CuCl}_2} 2\text{Cl}_2 + 2\text{H}_2\text{O} \] Step 3: Final Answer:
The statement that is not correct is that chlorine oxidizes iodine to periodic acid. It oxidizes it to iodic acid. Therefore, option (B) is the correct answer.