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Preparation of Bleaching Powder

March 9, 2013

INTRODUCTION TO PREPARATION OF BLEACHING POWDER :

Bleaching powder is  powder that contains calcium chloride and calcium hypocrite which is used in the solution as a bleaching agent.

Bleaching powder is also called as chloride of lime or chlorinated lime. The chemical name for Bleaching powder is Calcium Oxycloride.

Bleaching powder is prepared by passing gas state of chlorine over dry slaked lime (`Ca(OH)_2` ), this process will gives bleaching powder.

`Ca(OH)_2`  +  `Cl_2 `  `uarr`———>  `CaOCl_2`  + `H_2O`
(Calcium                                             (Bleaching powder)
Hydroxide or
Slaked lime)

preparation of bleaching powder reaction

Bleaching powder is prepared on a large scale by passing the chlorine gas through a solution that contains calcium hydroxide. Bleaching powder is also sold on the basis of the available chlorine, which is liberated when it is treated with the dilute acid. Bleaching powder is used for bleaching paper pulps and fabrics and for sterilizing water.

Calcium hypochlorite is used as a bleaching agent and disinfectant agent. The bleaching powder is also called as chlorinated lime (chloride of lime) which is used in error in the whitewash. Bleaching powder also causes irritation on the skin and eye.

Preparation of Bleaching powder

Hasen Clever Plant for the preparation of Bleaching Powder :

The HasenClever plant consists of four cylinder of cast iron. Each cylinder is about 2m to 3m long .Each cylinder is provided with the stirrer to ensure mixing of substances. There is an inlet that is present in the upper most cylinder for `Ca(OH)_2` . The bottom cylinder has an inlet that is present for `Cl_2` and outlet at the bottom for the bleaching powder to be accumulated. Each cylinder is connected to the other cylinder by means of pipes.

bleaching powder

In the preparation of bleaching powder ,we can get water(`H_2O` ).

Properties and uses of the bleaching powder

Properties of the Bleaching powder :

1)Bleaching powder is yellowish in colour and white powder and smells clorine.

2)Bleaching is soluble in water. The lime present is left behind as an insoluble salt so it is called chloride of lime.

3)When Bleaching powder is exposed to air ,it is oxydised to chlorine.

`CaOCl_2`  +   `CO_2`———>   `CaCO_3`  +  `Cl_2 `  `uarr`

4) Chlorine gas is produced ,when Bleaching powder is treated with excess of dilute acid.

`CaOCl_2`  +   `H_2SO_4` (dilute)   ———>  `CaSO_4`  + `H_2O`   +  `Cl_2 `  `uarr`

Uses of the Bleaching powder :

1) Bleaching powder is also used in the paper industry .

2) Bleaching powder is commonly used for bleaching clothes.

3) Bleaching powder is used to disinfect drinking water.

4) Bleaching powder is used in the manufacture of chloroform (CHCl3), an anaesthetic.

5) Bleaching powder is used as an oxidising agent.

6) Bleaching powder is used to shrink wool.

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