10.16 Starting with sodium chloride how would you proceed to prepare (i) sodium metal (ii) sodium hydroxide (iii) sodium peroxide (iv) sodium carbonate ?
(i) Sodium metal can be extracted from sodium chloride.In this process electrolysis of fused (40%) and (60%) at a temp. of 1123K in Downs cell.
steel cathode and graphite block is act as anode. sodium and calcium deposit at cathode .
(ii) can be prepared by the electrolysis of sodium chloride. By Castner- kellner process. A brine solution is electrolysed using a mercury cathode and a carbon anode. Sodium metal discharged at the cathode combines with mercury to form sodium amalgam. Chlorine gas is evolved at the anode.
(iii) NaCl is electrolysed for the formation of Na metal (in downs process). this sodium metal is then heated on aluminium trays in air to form sodium peroxide.
(iv) Sodium carbonate is preapred by solvay process. is precipitated in a reaction of sodium chloride and ammonium hydrogen carbonate.
this crystals are heatedto give sodium carbonate.