Bleaching Powder

📚 Key Concepts

🔹 Real-Life Example

The chlorine smell you notice in swimming pools comes from bleaching powder used to disinfect the water. Laundries use it to whiten clothes, and water treatment plants use it to kill harmful bacteria. However, its strong oxidizing nature means it can damage coloured fabrics.

Bleaching Powder (CaOCl₂): Also known as chloride of lime, it’s a yellowish-white powder with a strong smell of chlorine, used as a bleaching agent and disinfectant.

🧪 Preparation and Properties

🔸 Preparation Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O

🔸 Properties

• Yellowish-white powder
• Strong smell of chlorine
• Soluble in water
• Decomposes in presence of acids

🔸 Bleaching Action CaOCl₂ + H₂O → Ca(OH)₂ + HOCl HOCl → HCl + [O] (Nascent oxygen)

The nascent oxygen oxidizes coloured organic matter, making it colourless.

🔸 Uses

• Bleaching cotton and linen in textile industry
• Bleaching wood pulp in paper industry
• Disinfectant for water treatment
• Sterilizing wounds (in dilute solution)

🔍 Advanced: Oxidative Bleaching

Unlike sulphur dioxide (which causes temporary bleaching), bleaching powder causes permanent bleaching through oxidation.