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What is Bleaching Powder(CaOCl₂)

Bleaching powder is one of the most useful bleaching agents, particularly for textiles and paper. Chemically, bleaching powder is CaOCl2. It has been given different chemical names such as calcium oxychloride, calcium hypochlorite or chloride of lime.

Manufacturing of Bleaching Powder

It is manufactured by the action of chlorine gas on dry slaked lime. It is also called calcium oxychloride. It can be made by Hesen's clever plant or by Bachmann.

This plant consists of a number of cylinder inter connected with each other in a horizontal position. Cylinders are provided with rotating shafts having blades. Here, slaked lime is poured from the top through a hopper.

When the shaft rotates then revolving blades push the slaked lime in a forward direction. So it moves from one cylinder to another cylinder. Through the bottommost cylinder, chlorine gas is injected, which moves upward. In this way, upward-moving chlorine gas meets with downward-moving slaked lime and forms bleaching powder.

Ca(OH)2​+Cl2​→CaOCl₂​+H2​O

Properties of Bleaching Powder

1. Bleaching powder is a yellowish-white powder that smells exactly like chlorine.
2. Bleaching powder is soluble in water. However, some amount of white residue is always left on account of the presence of unreacted slaked lime.
3. Bleaching powder, on coming into contact with moist air containing carbon dioxide, liberates chlorine gas.
4. When bleaching powder is treated with an excess of a dilute acid, all the chlorine present in it is liberated. For example, when bleaching powder is treated with an excess of dilute sulphuric acid, all the chlorine present in it is liberated:

The chlorine produced by the action of a dilute acid on bleaching powder acts as a bleaching agent. Thus, the real bleaching agent present in bleaching powder is chlorine. The bleaching action of chlorine is due to its oxidising property

Quality of bleaching powder is measured by the percentage amount of chlorine it can liberate when treated with dilute hydrochloric acid. A standard bleaching powder contains 35% of chlorine.

Uses of Bleaching Powder (CaOCl₂)

1. It is used as an oxidising agent in many chemical industries.
2. Disinfecting drinking water to make it free from germs.
3. It is used for bleaching white cotton clothes in a laundry and cotton fabric in textile mills.
4. It is used for bleaching wood pulp in the paper industry.
5. It is used for disinfecting lavatories, drains and ditches.
6. It is used for making unshrinkable wool.
7. It is used in the manufacture of chloroform.

Conclusion

Bleaching powder is an important chemical compound used for cleaning, bleaching, and disinfecting purposes. Due to its ability to release chlorine, it is highly effective in killing harmful microorganisms and maintaining hygiene. Understanding bleaching powder and its uses is essential in chemistry and daily life applications.