How will you prepare the following
(a) sodium carbonate from sodium chloride
(b) Sodium thiosulphate from sodium sulphite
(c ) Sodium cyanide from sodium metal.
(d) Sodium silicate from silica.

Explanation

(a) The conversion is done in solvay process by passing a mixture of `NH_(3)` and `CO_(2)` vapours through saturated brine solution.
`CO_(2) + NH_(3) + H_(2)O to NH_(4)CO_(3)`
`NH_(4)HCO_(3) + NaCI to NaHCO_(3) + NH_(4) CI`
`2NaHCO_(3) overset("Heat")(to) Na_(2)S_(2)O_(3)`
(b) Sodium thiosulphate is prepared from sulphite by boiling with sulphur in an iron retort for nearly two hours
`Na_(2)SO_(3) + S overset(("Boil"))(to) Na_(2)S_(2)O_(3)`
(c ) Sodium in initially converted into sodamide by passing by ammonia gas over heated sodium
`2Na + 2NH_(2) to 2NaNH_(2) + H_(2)`
Molten sodamide is then reacted with charcoal to get sodium cyanide as follows :
`2NaNH_(2) + C to Na_(2)CN_(2) + 2H_(2)`
Sod. cyanamide
`Na_(2)CN_(2) + C to 2NaCN`
Sod. silicate