General Principles And Processes of Isolation Of Elements

Question

Sodium metal cannot be obtained by the electrolysis of aqueous sodium chloride solution.

Answer

The reduction potential values of sodium and water - 2.71 V and - 0.83 V respectively.

Na+(aq) + e → Na(s) E° = –2.71V
2H2O(l) + 2e → H2(g) + 20H E° = – 0.83 V

Thus Na+ has less tendency to change into a metal compared to H2O which has greater tendency to change into H2 gas. Therefore, H2O accepts electrons preferentially than Na+ in the electrolysis of aqueous chloride. Therefore, metal is not produced. 

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