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Karnataka Board PUCPUC Science 2nd PUC Class 12

Assertion: Electrolysis of NaCl solution gives chlorine at anode instead of O2. Reason: Formation of oxygen at anode requires overvoltage.

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Question

Assertion: Electrolysis of NaCl solution gives chlorine at anode instead of O2.

Reason: Formation of oxygen at anode requires overvoltage.

Options

  • Both assertion and reason are true and the reason is the correct explanation of assertion.

  • Both assertion and reason are true and the reason is not the correct explanation of assertion.

  • Assertion is true but the reason is false.

  • Both assertion and reason are false.

  • Assertion is false but reason is true.

MCQ
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Solution

Both assertion and reason are true and the reason is the correct explanation of assertion.

Explanation:

At the anode, the following oxidation reactions are possible.

\[\ce{Cl^{-} (aq) -> 1/2 Cl_{2}(g) + e^{-}; E = 1.36V}\]

\[\ce{2H2O(l) -> O2(g) + 4H^{-} (aq) + 4e^{-}; E = 1.23V}\]

Lower value of Ecell is perferenced but due to overvolatage chlorine is liberated at anode.

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Chapter 3: Electrochemistry - Exercises [Page 42]

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NCERT Exemplar Chemistry Exemplar [English] Class 12
Chapter 3 Electrochemistry
Exercises | Q V. 61. | Page 42

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