Answer:
(i) Sodium is obtained by carrying
electrolysis of a fused mixture of \[NaCl\] (40%) and \[CaC{{l}_{2}}\](60%) in Down's
cell at \[{{600}^{{}^\circ }}C\]using iron cathode and graphite anode. Na is
discharged at cathode and\[C{{l}_{2}}\]is evolved at the anode.
(ii) Sodium
hydroxide is obtained by electrolysis of aqueous solution of \[NaCl\] in
Castner-Kellner process.
In this
cell, mercury cathode and iron anode is used. The electrode processes are given
below:
\[NaCl\xrightarrow{Water}N{{a}^{+}}(aq)+C{{l}^{-}}(aq)\]
Anode: \[2C{{l}^{-}}\to
C{{l}_{2}}+2{{e}^{-}}\]
Cathode: \[N{{a}^{+}}+{{e}^{-}}\to
Na\]
\[Na+Hg\to
Na/Hg\](amalgam)
\[Na/Hg+{{H}_{2}}O\to
\underset{Caustic\,soda}{\mathop{NaOH}}\,+Hg+\frac{1}{2}{{H}_{2}}\uparrow \]
(iii) Sodium peroxide
is obtained by heating sodium in excess of air.
\[4Na+{{O}_{2}}\to 2N{{a}_{2}}O\]
\[2N{{a}_{2}}O+{{O}_{2}}\to
2N{{a}_{2}}{{O}_{2}}\]
(iv) Sodium
carbonate is obtained from aqueous \[NaCl\]by solvay's process
Step 1:
Brine \[(Aq\text{ }NaCI)\] is saturated with ammonia to form ammonical brime.
\[\underset{Brine}{\mathop{(NaCl+{{H}_{2}}O)}}\,+N{{H}_{3}}(g)\to
\underbrace{NaCl+N{{H}_{4}}OH}_{Ammonical\,Brine}\]
Step
2: Carbon dioxide when passed through ammonical brime, we get residue of
sodium bicarbonate.
\[N{{H}_{4}}OH+C{{O}_{2}}\to
N{{H}_{4}}HC{{O}_{3}}\]
\[N{{H}_{4}}HC{{O}_{3}}+NaCl\to
\underset{(Residue)}{\mathop{NaHC{{O}_{3}}}}\,+N{{H}_{4}}Cl\]
Thermal
decomposition of \[NaHC{{O}_{3}}\] gives the residue of sodium carbonate
\[2NaHC{{O}_{3}}\xrightarrow{\Delta
}\underset{sodium\,carbonate}{\mathop{N{{a}_{2}}C{{O}_{3}}}}\,+{{H}_{2}}O+C{{O}_{2}}\uparrow
\]
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