Page 5 - Microsoft Word - Module-2

with hydrogen chloride gas. Crystals of pure NaCl are

separated. CaCl and MgCl , being more soluble in
2
2
water, remain in solution.

Properties: It is white crystalline solid and m.p is

1081K.

Uses: It is used as common salt and used for the

manufacture of Na O , NaOH, Na CO , NaHCO etc.
2
2
3
3
2
(c)Sodium Hydroxide (Caustic Soda), NaOH
Preparation: (By Castner – Kellner cell)

A brine solution is electrolysed using mercury

cathode and a carbon anode. Sodium metal

discharged at the cathode forms sodium amalgam

which is treated with H O to give NaOH.
2
ு௚
+
Cathode: Na + e NaHg
-
2NaHg + 2H O 2NaOH + 2Hg + H
2
2
-
Anode: 2Cl Cl + 2e
-
2
Properties: It is white, translucent, deliquescent

solid.

Uses:

 It is used in soap, paper, textile, petroleum industry.

 Preparation of pure fats and oils.

 As a laboratory reagent.