Starting from sodium chloride, how will you proceed to prepare (i) sodium metal (ii) sodium hydrxide (iii) sodium peroxide (iv) sodium carbonate.

Explanation

(i) Sodium metal is manufactured by electrolysis of a fused mixture of NaCl (40%) and `CaCl_(2)` (60%) in Down's cell at 873 K using iron cathode and graphite anode .Na is liberated at the cathode while `Cl_(2)` is evolved at the anode ,
At cathode : `Na^(+)` (melt) `+ e^(-) to Na (l)`
At anode : `2 Cl^(-)` (melt) `to Cl_(2) (g) + 2 e^(-)`
(ii) Sodium hydroxide is manufactured by electrolysis of an aqueous solution of NaCl (brine ) in Castner Kellner cell using mercury cathode and carbon anode . Sodium metal which is discharged at the cathode combines with mercury to form sodium amalgam . `Cl_(2)` gas is evolved at the anode .
`{:("Cathode" : ,, Na^(+) + e^(-) to underset("Sodium")(Na) , ,, 2 Na + x Hg to underset("Sodium amalgam")(Na_(2)Hg_(x))), ("Anode" : ,, 2Cl^(-) to Cl_(2) + 2 e^(-) ,,):} `
The sodium amalgam thus obtained is treated with water to form sodium hydroxide and hydrogen gas
`Na_(2)Hg_(x) + 2H_(2)O to 2 NaOH + x Hg+ H_(2)`
(iii) Sodium peroxide is obtained by heating sodium in excess of air . The intially formed sodium oxide reacts with more `O_(2)` to form `Na_(2)O_(2)`.
`{:(4Na + O_(2) overset(Delta)(to) 2Na_(2)O), (2 Na_(2)O + O_(2) overset(Delta)(to) 2Na_(2)O_(2)):}`
(iv) Sodium carbonate is obtained by Solvay ammonia process as discussed in Ans