NEET
- Exam
- NEET
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- Chemistry
- Chapter
- Electrochemistry
NEET · Chemistry · Electrochemistry
Which reduction reaction occurs at the cathode during the...
Which reduction reaction occurs at the cathode during the electrolysis of sodium chloride solution?
Options
- ANa⁺ (aq) + e- → Na (s)
- BH2O(aq) + e- → ½ H2(g)
- CH2O (l ) + e- → ½H2(g) + OH⁻(aq)
- DCl⁻ (aq) → ½ Cl2(g) + e-
Correct answer
C. H2O (l ) + e- → ½H2(g) + OH⁻(aq)
Step-by-step solution
At the cathode there is competition between the following reduction reactions:Na⁺ (aq) + e- → Na (s) (Eo cell = – 2.71 V)H⁺(aq) + e- → ½ H2(g)(Eo cell= 0.00 V) The reaction with higher value of Eo is preferred and therefore, the reaction at the cathode during electrolysis is: H⁺ (aq) + e- → ½ H₂ (g) ( but H⁺ (aq) is produced by the dissociation of H₂O), i.e., H2O (l ) → H⁺ (aq) + OH⁻ (aq).