10.16. Starting with sodium chloride how would you proceed to prepare
(i) Sodium metal

(ii) Sodium hydroxide
(iii) Sodium peroxide

(iv) Sodium carbonate?

<p> (i) Sodium metal is manufactured by electrolysis of a fused mass of NaCl 40% and CaCl₂&nbsp;60% in Down’s cell at 873 K, using iron as cathode and graphite as anode. Na is liberated at the cathode.<br><strong>At cathode:</strong><br>Na⁺&nbsp;+ e^–&nbsp;→ Na (l)<br><strong>At anode:</strong><br>2Cl^–&nbsp; (melt) → Cl₂&nbsp; (g) + 2e^–.<br> (ii) Sodium hydroxide is manufactured by electrolysis of an aqueous solution of NaCl (brine) in Castner-Kellner cell.<br><strong>At cathode:</strong><br>Na⁺&nbsp;+ e^–&nbsp;→ Na<br>2Na + Hg → Na – Hg + 2H₂O<br>2Na- Hg + 2H₂O → 2NaOH +H₂&nbsp;+Hg<br><strong>At anode:</strong><br>Cl^–&nbsp;– e^–&nbsp;→ Cl<br>Cl + Cl→ Cl₂<br> (iii) Sodium peroxide:</p><p>Sodium is heated in excess of oxygen to form sodium peroxide. Initially, sodium oxide is obtained which reacts with more oxygen to form sodium peroxide.</p><p>4Na+O₂→2Na₂O</p><p>2Na₂O+O2→Na₂O₂<br> (iv)Sodium carbonate is obtained by Solvay ammonia process.<br>NaCl + NH₃ + H₂O + CO₂→ NaHCO₃→ + NH₄Cl</p><p>2NaHCO₃→ Na₂CO₃ + H₂O + CO₂</p>

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