When a dilute solution of sodium chloride (NaCl) is electrolyzed using graphite electrodes, the following half-reactions occur at the cathode and anode:
At the Cathode:
In the electrolysis of a dilute sodium chloride solution, reduction occurs at the cathode. Water is reduced to hydrogen gas in this case, rather than sodium ions (Na⁺) since the reduction of water is energetically more favorable. The half-equation can be written as:
\[ \text{2H}_2\text{O(l)} + 2e^- \rightarrow \text{H}_2(g) + 2\text{OH}^-(aq) \]
At the Anode:
At the anode, oxidation occurs. In a dilute sodium chloride solution, chloride ions (Cl⁻) are oxidized to chlorine gas. The half-equation for this reaction is:
\[ \text{2Cl}^-(aq) \rightarrow \text{Cl}_2(g) + 2e^- \]
Summary:
- Cathode Reaction: \( \text{2H}_2\text{O(l)} + 2e^- \rightarrow \text{H}_2(g) + 2\text{OH}^-(aq) \)
- Anode Reaction: \( \text{2Cl}^-(aq) \rightarrow \text{Cl}_2(g) + 2e^- \)
These reactions lead to the production of hydrogen gas at the cathode and chlorine gas at the anode during the electrolysis of dilute sodium chloride solution.
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