Electrolysis of a aqueous solution of sodium chloride produces

Options

A. Hydrogen gas at anode and chlorine at cathode
B. Hydrogen gas at cathode and oxygen at anode
C. Hydrogen gas at anode and sodium hydroxide at cathode
D. Chlorine gas at anode and sodium hydroxide at cathode.

Answer

To solve the question regarding the products of electrolysis of an aqueous solution of sodium chloride (NaCl), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Electrolysis Process**:
- Electrolysis involves passing an electric current through an electrolyte solution, which in this case is an aqueous solution of sodium chloride (NaCl).

2. **Determine the Ions Present**:
- In an aqueous solution of NaCl, the dissociation occurs as follows:
\[ \text{NaCl} \rightarrow \text{Na}^+ + \text{Cl}^- \]
- Additionally, water (H₂O) also dissociates into hydrogen ions (H⁺) and hydroxide ions (OH⁻):
\[ \text{H}_2\text{O} \rightarrow \text{H}^+ + \text{OH}^- \]
- Therefore, the ions present in the solution are Na⁺, Cl⁻, H⁺, and OH⁻.

3. **Identify the Electrodes**:
- The cathode is the negative electrode where reduction occurs, and the anode is the positive electrode where oxidation occurs.

4. **Reactions at the Cathode**:
- At the cathode, both Na⁺ and H⁺ ions can be reduced. The reduction reactions are:
- For Na⁺:
\[ \text{Na}^+ + e^- \rightarrow \text{Na} \quad (\text{Sodium metal}) \]
- For H⁺:
\[ 2\text{H}^+ + 2e^- \rightarrow \text{H}_2 \quad (\text{Hydrogen gas}) \]
- Since the reduction of H⁺ to form hydrogen gas requires less energy than the reduction of Na⁺, hydrogen gas (H₂) is produced at the cathode.

5. **Reactions at the Anode**:
- At the anode, Cl⁻ and OH⁻ ions can be oxidized. The oxidation reactions are:
- For Cl⁻:
\[ 2\text{Cl}^- - 2e^- \rightarrow \text{Cl}_2 \quad (\text{Chlorine gas}) \]
- For OH⁻:
\[ 4\text{OH}^- - 4e^- \rightarrow 2\text{H}_2\text{O} + \text{O}_2 \quad (\text{Oxygen gas}) \]
- The oxidation of Cl⁻ to form chlorine gas requires less energy compared to the oxidation of OH⁻ to form oxygen gas, hence chlorine gas (Cl₂) is produced at the anode.

6. **Conclusion**:
- Therefore, during the electrolysis of an aqueous solution of sodium chloride, hydrogen gas is liberated at the cathode and chlorine gas is liberated at the anode.

### Final Answer:
- **Hydrogen gas (H₂) at the cathode and Chlorine gas (Cl₂) at the anode.**

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