XII Chemistry BIEK Topic - Bleaching Powder (Short Note)

Bleaching Powder (Short Note)
Definition
Bleaching powder is a white amorphous powder with smell of chlorine.




Formula of Bleaching Powder
On the basis of available percentage of chlorine, the formula of bleaching powder was suggested by Professor Odling. The formula is given by

Ca(OCl)Cl or CaOCl2




Preparation of Bleaching Powder
Bleaching powder is prepared on the large scale by Hasen Clever Process. The plant consist of a number of iron cylinders in which chlorine is brought in contact with slaked lime [Ca (OH)2].

Ca(OH)2 + Cl2 ----> CaOCl2 + H2O




Chemical Reactions of Bleaching Powder
1. In aqueous solution bleaching powder liberates chlorine.

CaOCl2 + H2O ----> Ca(OH)2 + Cl2


2. It reacts with acids to set free chlorine.

CaOCl2 + 2HCl ----> CaCl2 + H2O + Cl2


3. It reacts with atmospheric CO2 and moisture to give following reaction.

2CaOCl2 + CO2 + H2O ----> CaCO3 + CaCl2 + 2HOCl




Uses of Bleaching Powder
1. It is used for sterilization of drinking water.

2. It is used for bleaching of cotton, linen and paper pulp.

3. It is used for the preparation of Cl2 gas and chloroform (CHCl3).