Question

How is sodium metal extracted? Explain with the help of equation of the reaction involved.

Answer 1

Sodium metal is extracted by the electrolytic reduction (or electrolysis) of molten sodium chloride. When electric current is passed through molten sodium chloride, it decomposes to form sodium metal and chlorine gas.

\[\ce{\underset{(Molten)}{\underset{Sodium chloride}{2NaCl_{(l)}}} ->[Electrolysis] \underset{Sodium metal}{2Na_{(s)}} + \underset{Chlorine gas}{Cl2_{(g)}}}\]

Molten sodium chloride (NaCl) comprises free sodium ions (Na⁺) and free chloride ions (Cl⁻). During the electrolysis of molten sodium chloride, the subsequent processes occur at the two electrodes.

The positively charged sodium ions (Na⁺) are drawn towards the cathode (negative electrode). The sodium ions gain electrons from the cathode and are reduced to form sodium atoms (or sodium metal).

At cathode: \[\ce{\underset{(From molten NaCl)}{\underset{Sodium ions}{2Na+}} + \underset{(From cathode)}{\underset{Electrons}{2e-}} -> \underset{(Sodium metal)}{\underset{Sodium atoms}{2Na}}}\]

Thus, sodium metal is produced at the cathode (negative electrode).

The negatively charged chloride ions (Cl⁻) are drawn towards the anode (positive electrode). The chloride ions donate electrons to the anode and undergo oxidation to produce chlorine gas.

At anode: \[\ce{\underset{(From molten NaCl)}{\underset{Chlorine ions}{2Cl-}} - \underset{(Given to anode)}{\underset{Electrons}{2e-}} -> \underset{Chlorine gas}{Cl2}}\]

Thus, chlorine gas is formed at the anode (positive electrode).