Bleaching powder (CaOCl₂) has several important uses in daily life and industry. Its two main uses are: (1) as a bleaching agent for cotton, linen, and wood pulp in the textile and paper industries, and (2) as a disinfectant for drinking water and swimming pools. It is also used for making chloroform and as a weed killer.
Two main uses: (1) bleaching agent for cotton/linen/wood pulp, (2) disinfectant for drinking water and swimming pools.
Active agent is HOCl (hypochlorous acid) which releases nascent oxygen for bleaching.
Used in the manufacture of chloroform (CHCl₃).
Used as a weed killer and deodorising agent.
Used in paper industry to bleach wood pulp.
Kills bacteria and pathogens in water — makes water safe for drinking.
Used to sterilise hospitals, drains, and sewage.
Bleaching action is due to nascent [O] which oxidises coloured compounds to colourless ones.
Bleaching powder is used instead of chlorine gas in the textile industry because it is easier to handle and transport.
Manufacturing chloroform (CHCl₃): Bleaching powder reacts with acetone or ethanol to produce chloroform: CH₃COCH₃ + 3CaOCl₂ → CHCl₃ + Ca(CH₃COO)₂ + CaCl₂ + H₂O
Oxidising agent in chemical reactions: Used in organic synthesis as an oxidising agent.
Weed killer: Dilute solutions are used to destroy weeds in agricultural fields.
Deodorising: Used to remove foul smells from drains, sewage, and public places.
Paper industry: Used to bleach wood pulp in paper manufacturing.
Hospital disinfection: Used to sterilise operation theatres, floors, and equipment.
The bleaching action of bleaching powder is due to nascent oxygen (atomic oxygen) released by hypochlorous acid:
Step 1: CaOCl₂ + H₂O → Ca(OH)₂ + 2HOCl Step 2: HOCl → HCl + [O] (nascent oxygen) Step 3: Coloured substance + [O] → Colourless substance
Nascent oxygen is extremely reactive and oxidises the chromophores (colour-causing groups) in fabrics and dyes, making them colourless.
Bleaching is irreversible — it permanently removes colour by chemical oxidation, unlike physical methods like washing.
Two main uses of bleaching powder are: (1) As a bleaching agent — used to bleach cotton, linen, and wood pulp in the textile and paper industries; (2) As a disinfectant — used to purify drinking water and disinfect swimming pools by killing bacteria and pathogens.
Bleaching powder releases HOCl in water, which further releases nascent oxygen [O]. This highly reactive nascent oxygen oxidises the chromophores (colour-producing groups) in fabrics, making them colourless: HOCl → HCl + [O]; Coloured matter + [O] → Colourless matter.
Bleaching powder releases chlorine or HOCl in water, which kills harmful bacteria and pathogens. A small amount is added to drinking water supplies and swimming pools. The chlorine destroys disease-causing microorganisms, making water safe for use.
Yes. Bleaching powder reacts with acetone or ethanol to produce chloroform (CHCl₃): CH₃COCH₃ + 3CaOCl₂ → CHCl₃ + Ca(CH₃COO)₂ + CaCl₂ + H₂O. This is one of the laboratory methods for preparing chloroform.
Yes. Dilute solutions of bleaching powder are used to destroy weeds in agricultural fields. The chlorine released by bleaching powder kills the plant tissue.
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