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  • Stuck here, help me understand: In Castner-Kellner cell for production of sodium hydroxide:

In Castner-Kellner cell for production of sodium hydroxide:

  • Option 1)

    Brine is electrolyzed with Pt electrodes

  • Option 2)

    Brine is electrolyzed using graphite electrodes

  • Option 3)

    Molten sodium chloride is electrolyzed

  • Option 4)

    Sodium amalgam is formed at mercury cathode

 

Answers (1)

best_answer

As we learnt in

Preparation of NaOH by castner-Kellner cell -

Also known as mercury cathode process by electrolysis of aq.solution of brine

cathode:  Na^{+}+e^{-\overset{Hg}{\rightarrow}} Na-amalgam

Anode: Cl^{-}+\frac{1}{2}Cl_{2}+e^{-}

- wherein

Cell comprises of three compartments

Outer compartment:Brine solution is electrolysed

Central compartment: 2% NaOH solution and H{_2}

 

 

In the Castner Kellner cell, 

At cathode, Na^{+}+e^{-}\overset{Hg}{\longrightarrow} Na- amalgam

At anode, Cl^{-}\longrightarrow \frac{1}{2}Cl_{2}+e^{-}

\therefore Sodium Amalgam is formed at cathode.


Option 1)

Brine is electrolyzed with Pt electrodes

This option is incorrect.

Option 2)

Brine is electrolyzed using graphite electrodes

This option is incorrect.

Option 3)

Molten sodium chloride is electrolyzed

This option is incorrect.

Option 4)

Sodium amalgam is formed at mercury cathode

This option is correct.

Posted by

prateek

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