Question -
Answer -
(a) Sodium can beextracted from sodium chloride by Downs process.
This process involves the electrolysis offused NaCl (40%) and CaCl2 (60 %) at a temperature of 1123 K inDowns cell.
Steelis the cathode and a block of graphite acts as the anode. Metallic Na and Caare formed at cathode. Molten sodium is taken out of the cell and collectedover kerosene.
(ii) Sodium hydroxide canbe prepared by the electrolysis of sodium chloride. This is calledCastner–Kellner process. In this process, the brine solution is electrolysedusing a carbon anode and a mercury cathode.
Thesodium metal, which is discharged at cathode, combines with mercury to form anamalgam.
(iii) Sodium peroxide
First,NaCl is electrolysed to result in the formation of Na metal (Downs process).
This sodium metal is then heated onaluminium trays in air (free of CO2) to form its peroxide.
(iv) Sodium carbonate isprepared by Solvay process. Sodium hydrogen carbonate is precipitated in areaction of sodium chloride and ammonium hydrogen carbonate.
Thesesodium hydrogen carbonate crystals are heated to give sodium carbonate.
