Chapter 16 — Chemistry in Everyday Life — is the easiest and most relatable chapter! It covers how chemistry impacts our daily lives through drugs, soaps, detergents, and food additives. This chapter carries 3-4 marks in Board exams and is purely factual. Just memorise the classifications, examples, and mechanisms — no numericals!
Key Concepts
Drugs and Their Classification
Classification Based on Pharmacological Effect
| Category | Function | Examples |
|---|---|---|
| Analgesics | Relieve pain | Aspirin, Paracetamol, Morphine |
| Antipyretics | Reduce fever | Aspirin, Paracetamol |
| Antiseptics | Kill/prevent growth of microorganisms (on living tissue) | Dettol, Bithionol, Iodine tincture |
| Disinfectants | Kill microorganisms (on non-living surfaces) | Chlorine, SO₂, phenol (1% solution) |
| Antibiotics | Kill or inhibit bacteria | Penicillin, Amoxicillin, Tetracycline |
| Antacids | Neutralise excess stomach acid | Ranitidine, Omeprazole, Eno (NaHCO₃) |
| Antihistamines | Block histamine action (allergies) | Brompheniramine, Terfenadine |
| Tranquilizers | Reduce anxiety/tension | Valium, Chlordiazepoxide |
| Antimicrobials | Kill/inhibit microorganisms | Antibiotics, antiseptics, disinfectants |
Drug-Target Interaction
1. Enzymes as drug targets:
– Competitive inhibitor: drug competes with substrate for active site
– Non-competitive inhibitor: drug binds at different site, changes enzyme shape
2. Receptors as drug targets:
– Agonist: mimics natural messenger, activates receptor (e.g., morphine)
– Antagonist: blocks receptor, prevents natural messenger from binding (e.g., antihistamines)
Important Drug Categories — Details
Analgesics:
| Type | Mechanism | Examples |
|---|---|---|
| Non-narcotic (Non-addictive) | Inhibit prostaglandin synthesis | Aspirin, Ibuprofen, Paracetamol |
| Narcotic (Opioids) | Bind to opioid receptors in brain | Morphine, Codeine, Heroin |
Antibiotics:
- Bactericidal: Kill bacteria (e.g., Penicillin, Ofloxacin, Aminoglycosides)
- Bacteriostatic: Inhibit growth (e.g., Erythromycin, Tetracycline, Chloramphenicol)
- Broad spectrum: Effective against many types (Tetracycline, Chloramphenicol)
- Narrow spectrum: Effective against specific types (Penicillin G)
Antacids:
- H₂ receptor blockers: Block histamine from stimulating acid secretion (Ranitidine, Cimetidine)
- Proton pump inhibitors: Block H⁺/K⁺ ATPase (Omeprazole — “Losec”)
- Simple antacids: Neutralise acid directly (NaHCO₃, Mg(OH)₂, Al(OH)₃)
Antiseptics vs Disinfectants
| Property | Antiseptic | Disinfectant |
|---|---|---|
| Applied on | Living tissue (wounds, skin) | Non-living surfaces (floor, instruments) |
| Concentration | Dilute/mild | Concentrated/strong |
| Examples | Dettol, Savlon, Tincture of iodine (2-3% I₂ in alcohol), Bithionol (in soaps) | 1% phenol, 0.2% chlorine in water, SO₂ in low conc. |
Chemicals in Food
Food Additives
| Type | Purpose | Examples |
|---|---|---|
| Artificial Sweeteners | Provide sweetness without calories | Saccharin (550× sweeter), Aspartame (100×), Sucralose (600×), Alitame (2000×) |
| Preservatives | Prevent spoilage by bacteria/fungi | Sodium benzoate (C₆H₅COONa), Sodium metabisulphite, Sorbic acid |
| Antioxidants | Prevent oxidative rancidity of fats | BHT (butylated hydroxytoluene), BHA, Sulphur dioxide |
Cleansing Agents
Soaps
Example: CH₃(CH₂)₁₆COONa (sodium stearate)
Saponification: Fat/Oil + NaOH → Soap + Glycerol
(CH₂OOCR)₃ + 3NaOH → 3RCOONa + C₃H₅(OH)₃
Soap Structure — Micelle Formation
Soap molecule has two parts:
- Hydrophilic head: −COO⁻Na⁺ (ionic, water-loving → dissolves in water)
- Hydrophobic tail: Long hydrocarbon chain (non-polar, water-hating → dissolves in grease)
When soap is added to dirty water, the hydrophobic tails embed in grease, while hydrophilic heads stay in water. This forms a micelle — a spherical cluster with grease trapped inside. The micelle is soluble in water → grease washes away!
Synthetic Detergents
Types:
1. Anionic: −SO₃⁻Na⁺ or −OSO₃⁻Na⁺ (sodium lauryl sulphate — in shampoos)
2. Cationic: Quaternary ammonium salt (cetyl trimethyl ammonium bromide — in hair conditioner)
3. Non-ionic: No charge (polyethylene glycol stearate — in liquid dish soap)
Biodegradability
- Biodegradable: Linear hydrocarbon chain → easily broken by bacteria (e.g., linear alkylbenzene sulphonates)
- Non-biodegradable: Branched chain → resistant to bacterial action → pollutes water (e.g., branched alkylbenzene sulphonates — now banned in many places)
Important Definitions
| Term | Definition |
|---|---|
| Drug | Chemical substance that modifies body function for therapeutic benefit |
| Antibiotic | Chemical substance produced by microorganisms that kills/inhibits other microorganisms |
| Analgesic | Drug that relieves pain without causing unconsciousness |
| Antiseptic | Chemical that kills/prevents growth of microorganisms on living tissue |
| Antioxidant | Substance that prevents oxidation of food (rancidity) |
| Micelle | Spherical cluster of soap molecules with grease trapped in hydrophobic core |
Solved Examples — NCERT Based
Example 1: Drug Classification
Q: Classify the following drugs: (a) Ranitidine (b) Penicillin (c) Chloramphenicol (d) Aspirin
Solution:
(a) Ranitidine — Antacid (H₂ receptor blocker)
(b) Penicillin — Antibiotic (bactericidal, narrow spectrum)
(c) Chloramphenicol — Antibiotic (bacteriostatic, broad spectrum)
(d) Aspirin — Analgesic + Antipyretic + Anti-inflammatory (non-narcotic)
Example 2: Soap vs Detergent
Q: Why do detergents work in hard water but soaps don’t?
Solution: Soaps are sodium salts of fatty acids. In hard water, Ca²⁺/Mg²⁺ ions replace Na⁺ to form insoluble calcium/magnesium stearate (scum) → no cleaning action.
Detergents are sodium salts of sulphonic acids or sulphates. Their Ca²⁺/Mg²⁺ salts are soluble → no scum → effective cleaning even in hard water.
Example 3: Antiseptic vs Disinfectant
Q: What is the difference between an antiseptic and a disinfectant? Can the same substance be both?
Solution: Antiseptics are applied on living tissue (wounds, skin). Disinfectants are used on non-living surfaces (floors, surgical instruments). Yes, the same substance can be both — at different concentrations. Example: 0.2% phenol is an antiseptic; 1% phenol is a disinfectant.
Example 4: Micelle Formation
Q: Explain how soap cleans dirty clothes.
Solution: Soap molecules have a hydrophobic tail (dissolves in grease) and a hydrophilic head (dissolves in water). When added to dirty water:
1. Hydrophobic tails penetrate into grease/oil on fabric
2. Hydrophilic heads remain in water
3. This forms micelles — spherical clusters with grease trapped in the centre
4. Micelles are soluble in water → grease is emulsified and washed away with rinsing
Important Questions for Board Exams
1 Mark Questions
- What is the difference between antiseptic and disinfectant?
- Name one broad-spectrum antibiotic.
- What are antioxidants? Give one example.
- Why does soap not work in hard water?
2 Mark Questions
- What are analgesics? Distinguish between narcotic and non-narcotic analgesics.
- Explain the cleansing action of soap (micelle formation).
- What is the difference between bactericidal and bacteriostatic antibiotics?
- Why is aspartame not used in cooking?
3 Mark Questions
- What are drugs? How do they interact with enzyme targets? Explain competitive and non-competitive inhibition.
- Describe the types of detergents: anionic, cationic, and non-ionic with examples.
- What are food preservatives? Name three and explain their role.
5 Mark Questions
- What are antibiotics? How are they classified? Discuss broad-spectrum vs narrow-spectrum and bactericidal vs bacteriostatic with examples.
- Explain soaps and detergents. How do they differ? Describe the cleansing action of soap with a diagram of micelle. Why do detergents cause water pollution?
Quick Revision Points
- Analgesics: non-narcotic (aspirin, paracetamol) and narcotic (morphine)
- Antibiotics: bactericidal (kill) vs bacteriostatic (inhibit); broad vs narrow spectrum
- Antacids: simple (NaHCO₃), H₂ blockers (ranitidine), PPIs (omeprazole)
- Antiseptic: living tissue (dettol, iodine); Disinfectant: surfaces (1% phenol, Cl₂)
- Artificial sweeteners: saccharin (550×), aspartame (100×, no heat), alitame (2000×)
- Soap = RCOONa (fails in hard water → scum)
- Detergent = RSO₃Na (works in hard water → soluble Ca/Mg salts)
- Micelle: hydrophobic tail in grease + hydrophilic head in water → emulsification
- Biodegradable: linear chain; Non-biodegradable: branched chain
- Cationic detergents: germicidal → used in hair conditioners
Chapter Navigation
Previous: Polymers Class 12 Notes
Next: This is the last chapter
Related Chapters in Class 12 Chemistry
Practice What You Learned
Test yourself with our JEE Main Mock Test Set 1 to see how well you’ve mastered the concepts.