Question

Which one of the following electrolytes is used in Down's process of extracting sodium metal?

• A. $NaCl+KCl+KF$
• B. $N{a}_{2}C{O}_3$
• C. $NaOH$
• D. $NaHC{O}_3$

Answer 1

The correct option is A $NaCl+KCl+KF$

The Downs cell uses a carbon anode and an iron cathode. The preferred electrolyte is fused sodium chloride. Though solid sodium chloride
is a poor conductor of electricity, in the fused state the sodium and chloride ions are mobilized and thus become charge carriers.

Some $KCl$ and even $KF$ are added to the electrolyte to lower the temperature required to keep the electrolyte liquid.
Sodium chloride melts at 801 ° C, but a salt mixture could be fused at a temperature as low as 507 °C.

The anode reaction is:
$2C{l}^{-}⟶C{l}_2\left(g\right)+2e^{-}$

The cathode reaction is:
$2N{a}^{+}+2e^{-}⟶2Na\left(l\right)$

Overall reaction:
$2N{a}^{+}+2C{l}^{-}⟶2Na\left(l\right)+C{l}_2\left(g\right)$