Chlor-Alkali Process: Electrode Products Explained

The chlor-alkali process involves the electrolysis of a concentrated aqueous solution of sodium chloride (brine).

Electrode Reactions

During electrolysis, specific chemical reactions occur at the cathode and anode:

• Cathode (Negative Electrode): Reduction occurs here. Water molecules are reduced to form hydrogen gas (\(H_2\)) and hydroxide ions (\(OH^-\)).
  Reaction: \(2H_2O(l) + 2e^- \rightarrow H_2(g) + 2OH^-(aq)\)
• Anode (Positive Electrode): Oxidation occurs here. Chloride ions (\(Cl^-\)) are oxidized to form chlorine gas (\(Cl_2\)).
  Reaction: \(2Cl^-(aq) \rightarrow Cl_2(g) + 2e^-\)

Overall Products

The key products formed are:

• Hydrogen Gas (\(H_2\)): Released at the cathode.
• Chlorine Gas (\(Cl_2\)): Released at the anode.
• Sodium Hydroxide (\(NaOH\)): Formed in the solution as sodium ions (\(Na^+\)) combine with the hydroxide ions (\(OH^-\)) produced at the cathode. \(Na^+(aq) + OH^-(aq) \rightarrow NaOH(aq)\)

Therefore, hydrogen gas is released at the cathode and chlorine gas at the anode.

This corresponds to Option 1.