Question

During the electrolysis of molten sodium chloride, the reaction which occurs at the cathode is

• A. ${\text{Na}}^{+}+{\text{e}}^{-}\to \text{Na(s)}$
• B. $\text{Na(s)}\to {\text{Na}}^{+}+{\text{e}}^{-}$
• C. $2{\text{Cl}}^{-}\to {\text{Cl}}_2\text{(g)}+2{\text{e}}^{-}$
• D. ${\text{Cl}}_2\text{(g)}+2{\text{e}}^{-}\to 2{\text{Cl}}^{-}$

Answer 1

The correct option is A

${\text{Na}}^{+}+{\text{e}}^{-}\to \text{Na(s)}$

During the electrolysis of molten sodium chloride, the ions present are sodium and chlorine ions. Sodium ions are cations which are attracted to the cathode and chloride ions are anions which are attracted to anodes. Each sodium ion gains one electron to form the sodium atom. Each chloride ion loses one electron to form chlorine atoms. The reactions takes place as follows:

At cathode: ${\text{Na}}^{+}+{\text{e}}^{-}\to \text{Na(s)}$

At anode: $2{\text{Cl}}^{-}\to {\text{Cl}}_2\text{(g)}+2{\text{e}}^{-}$

Overall reaction: $2{\text{Na}}^{+}+2{\text{Cl}}^{-}\to 2\text{Na (s)}+{\text{Cl}}_2\text{(g)}$