Ch 16 covers the role of chemistry in everyday life — drugs and medicines (analgesics, antibiotics, antiseptics, antacids), food chemistry (preservatives, sweeteners), and cleansing agents (soaps, detergents).
Analgesics: pain relief (aspirin — non-narcotic, morphine — narcotic). Antibiotics: kill/inhibit bacteria (penicillin — bactericidal, tetracycline — bacteriostatic). Antiseptics: applied on living tissue (Dettol, boric acid). Disinfectants: inanimate objects (Cl₂, SO₂). Antacids: neutralise stomach acid (ranitidine — H₂ receptor antagonist, omeprazole — proton pump inhibitor). Antihistamines: block histamine receptors (brompheniramine).
Preservatives: sodium benzoate, potassium metabisulphite. Artificial sweeteners: aspartame, saccharin, sucralose (non-caloric). Antioxidants: BHT, BHA. Soaps: RCOO⁻Na⁺ (don't work in hard water — form scum). Detergents: RSO₃⁻Na⁺ (work in hard water). Micelle formation: hydrophobic tail traps grease, hydrophilic head dissolves in water.
Download: https://ncert.nic.in/textbook/pdf/lech207.pdf | Part II: https://ncert.nic.in/textbook/pdf/lech2ps.zip
Hard water contains Ca²⁺ and Mg²⁺ ions. Soaps (sodium salts of long-chain fatty acids) react with these ions to form insoluble calcium/magnesium salts (scum), preventing lather formation. Detergents (sodium salts of long-chain sulphonic acids) form soluble calcium/magnesium salts, so they continue to work effectively in hard water.
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