Question

In the electrolysis of molten \( \mathrm{NaCl} \), what is produced at the cathode?

• A. Chlorine gas
• B. Sodium metal
• C. Hydrogen gas
• D. Oxygen gas

Hint:

Cations are reduced at the cathode; anions are oxidized at the anode.

Answer 1

The Correct Option is B

In the electrolysis of molten \( \mathrm{NaCl} \), an ionic compound consisting of sodium ions (\( \mathrm{Na}^+ \)) and chloride ions (\( \mathrm{Cl}^- \)), we aim to determine what is produced at the cathode.

During electrolysis, the compound is melted to free the ions, allowing them to move to the respective electrodes. The cathode is the negatively charged electrode, which attracts cations (positive ions).

The key reactions at each electrode in the electrolysis of molten \( \mathrm{NaCl} \) are as follows:

• At the cathode: Sodium ions (\( \mathrm{Na}^+ \)) are reduced by gaining electrons to form sodium metal.
  \( \mathrm{Na}^+ + e^- \rightarrow \mathrm{Na} \)
• At the anode: Chloride ions (\( \mathrm{Cl}^- \)) are oxidized by losing electrons to form chlorine gas.
  \( 2\mathrm{Cl}^- \rightarrow \mathrm{Cl}_2 + 2e^- \)

Since the cathode attracts sodium ions and they are reduced to sodium metal, the product formed at the cathode during the electrolysis of molten \( \mathrm{NaCl} \) is sodium metal.

Answer 2

During the electrolysis of molten \( \mathrm{NaCl} \) (sodium chloride), the compound is broken down into its constituent elements by passing an electric current through it. The process occurs in an electrolytic cell, where the electrolyte is the molten sodium chloride. The electricity causes chemical reactions at the electrodes, resulting in the separation of the compound into different elements.

The key reactions occurring during this process are:

• At the cathode (negative electrode): Reduction occurs. Sodium ions (\( \mathrm{Na^+} \)) in the molten state are reduced to form sodium metal. The half-reaction is represented as:
  \( \mathrm{Na^+} + e^- \rightarrow \mathrm{Na(s)} \)
• At the anode (positive electrode): Oxidation takes place. Chloride ions (\( \mathrm{Cl^-} \)) are oxidized to produce chlorine gas. The half-reaction is:
  \( 2\mathrm{Cl^-} \rightarrow \mathrm{Cl_2(g)} + 2e^- \)

The overall reaction for the electrolysis of molten sodium chloride can be expressed as:
\( 2\mathrm{NaCl(l)} \rightarrow 2\mathrm{Na(s)} + \mathrm{Cl_2(g)} \)

Thus, the product at the cathode is sodium metal, which is deposited as it gains electrons from the external circuit. 
Therefore, the correct answer is: Sodium metal