Question

Which of the following is evolved/deposited at anode when electrolysis of molten $NaCl$ using inert platinum electrodes is carried out?

• A. $Na\left(s\right)$
• B. $H_2\left(g\right)$
• C. $HCl\left(g\right)$
• D. $C{l}_2\left(g\right)$

Answer 1

The correct option is D $C{l}_2\left(g\right)$

Electrolysis of molten $NaCl$ with $Pt$ electrode:
In molten $NaCl$ , the ions $N{a}^{+}$ and $C{l}^{-}$ are present in molten form
Reaction at anode :
$2C{l}^{-}\left(l\right)\rightleftharpoons C{l}_2\left(g\right)+2e^{-}$
So, chlorine gas is given at anode.

Reaction at cathode :
$N{a}^{+}\left(l\right)+e^{-}\rightleftharpoons Na\left(s\right)$
At cathode, sodium metal is there.

Net reaction:
$2N{a}^{+}\left(l\right)+2C{l}^{-}\left(l\right)\rightleftharpoons 2Na\left(s\right)+C{l}_2\left(g\right)2NaCl\left(l\right)\rightleftharpoons 2Na\left(s\right)+C{l}_2\left(g\right)$