(i) Sodium metal is prepared by electrolysis of fused NaCl at 873 K using iron cathode and graphite anode (Down’s cell).
NaCl ⇌ Na++Cl−
At anode : 2Cl− → 2Cl+2e− → Cl2
At cathode : Na++e− → Na
(ii) Sodium hydroxide is prepared by electrolysis of aqueous solution of NaCl using Hg cathode and carbon anode.
(Castner-Kellner cell) : NaCl ⇌ Na++Cl−
At cathode : Na++e−

Hg

→

Na-amalgam
At anode : Cl− →

1

2

Cl2+e−
Na - amalgam is treated with water to give NaOH and H2 :
2Na-amalgam + 2H2O → 2NaOH+2Hg+H2
(iii) Sodium chloride to sodium peroxide : NaCl ⇌ Na++Cl−
At anode : 2Cl− → 2Cl+2e− → Cl2
At cathode : Na++e− → Na
Sodium is heated in excess of air.
2Na + O2

Δ

→

Na2O2.
(iv) Sodium hydrogen carbonate is prepared by passing CO2 through NaCl solution saturated with NH3.NaHCO3 formed is heated to give Na2CO3.
(Solvay process) :
NH3+H2O+CO2 + NaCl → NaHCO3+NH4Cl
2NaHCO3 Na2CO3 + H2O + CO2