Question

In the electrolysis of molten NaCl, the product obtained at the cathode is:

• A. Cl gas
• B. Na metal
• C. NaOH
• D. H gas

Hint:

Always distinguish between molten and aqueous electrolysis. In aqueous \( NaCl \) electrolysis, hydrogen gas (\( H_2 \)) is obtained at the cathode instead of sodium metal because water is easier to reduce than sodium ions.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
We need to identify the substance formed at the cathode during the electrolysis of sodium chloride in its liquid (molten) state.
Step 2: Key Formula or Approach:
Recall that in any electrolytic cell:
1. Cathode is the negative electrode where Reduction (gain of electrons) occurs.
2. Anode is the positive electrode where Oxidation (loss of electrons) occurs.
Step 3: Detailed Explanation:
In molten NaCl, the only ions present are \( Na^+ \) and \( Cl^- \). There is no water to compete at the electrodes.
1. At the Cathode: The positive sodium ions (\( Na^+ \)) move toward the negative cathode. They gain one electron each to form neutral sodium atoms.
\[ Na^+ + e^- \rightarrow Na(l) \]
Hence, sodium metal is produced.
2. At the Anode: The negative chloride ions (\( Cl^- \)) move toward the positive anode. They lose electrons to form chlorine gas.
\[ 2Cl^- \rightarrow Cl_2(g) + 2e^- \]
Step 4: Final Answer:
The product obtained at the cathode during the electrolysis of molten NaCl is sodium (Na) metal.