Question

The incorrect statement about Castner-Kellner cell process is

• A. Sodium hydroxide is prepared
• B. Brine solution is the electrolyte
• C. Mercury acts as anode and carbon rod acts as cathode
• D. Chlorine gas liberates at anode

Hint:

Remember the electrode definitions: AN-OX (Anode is Oxidation) and RED-CAT (Reduction is at Cathode). In the Castner-Kellner cell, Cl⁻ is oxidized to Cl₂ at the anode, and Na⁺ is reduced to Na at the mercury cathode.

Answer 1

The Correct Option is C

Step 1: Understanding Castner-Kellner Cell: The Castner-Kellner cell is used for the manufacture of Sodium Hydroxide (\( \text{NaOH} \)). It involves the electrolysis of brine solution (\( \text{NaCl} \)).
Step 2: Electrode Configurations: - Cathode: A flowing layer of Mercury (Hg) acts as the cathode. Here, sodium ions are discharged to form sodium amalgam (\( \text{Na-Hg} \)). Reaction: \( \text{Na}^+ + e^- \xrightarrow{\text{Hg}} \text{Na-Hg} \) - Anode: Carbon (Graphite) rods or Titanium anodes are used. Here, chloride ions are oxidized to chlorine gas. Reaction: \( 2\text{Cl}^- \to \text{Cl}_2 \uparrow + 2e^- \)
Step 3: Analyzing the Options: (A) Correct. NaOH is the product. (B) Correct. Brine is used. (C) Incorrect. The statement says Mercury is anode and Carbon is cathode. It is actually the opposite: Mercury is Cathode and Carbon is Anode. (D) Correct. \( \text{Cl}_2 \) is evolved at the anode.