Class 12 Chemistry Chapter 16 Notes: Chemistry in Everyday Life | Important Questions & PYQs

 Class 12 Chemistry Chapter 16 Chemistry in Everyday Life Notes

🔹 16.1 Drugs and Their Classification

✔ What are Drugs?

• Drugs are chemical substances used to diagnose, prevent or treat diseases

• They affect biochemical processes in the body

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✔ Why Drugs Must Be Taken Carefully

• In correct dose → medicine

• In excess dose → poison

• Hence, doctor consultation is necessary

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✔ Classification of Drugs

Drugs are classified on the basis of:

1. Pharmacological effect
   → Effect on body (antacids, analgesics, antibiotics)

2. Drug action
   → Action on a particular biochemical process

3. Chemical structure
   → Helps in designing similar drugs with less toxicity

4. Molecular targets
   → Interaction with enzymes, receptors, proteins

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🔹 16.2 Drug–Target Interaction

✔ Target Molecules

• Most drugs act on proteins

• Other targets: enzymes, carbohydrates, lipids, nucleic acids

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✔ How Drugs Work

• Drugs bind to active sites of enzymes/receptors

• Interaction involves:

  • Hydrogen bonding

  • Ionic interactions

  • Dipole–dipole forces

  • Van der Waals forces

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✔ Lead Compounds

• Compounds that show biological activity

• Used as a base to develop better drugs

• Can be obtained from natural sources or synthesis

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🔹 16.3 Therapeutic Action of Drugs

✔ Antacids

• Used to treat excess stomach acidity

• Examples:

  • Ranitidine

  • Cimetidine

🔹 Better than NaHCO₃ / Mg(OH)₂ because:

• They block histamine receptors

• Reduce acid secretion instead of neutralising it

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✔ Antihistamines

• Prevent allergic reactions

• Do not interfere with antacids

• Act on different receptors

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✔ Antidepressants / Tranquilizers

• Used in depression

• Increase level of noradrenaline

• Examples:

  • Iproniazid

  • Phenelzine

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✔ Antibiotics

• Kill or inhibit growth of bacteria

Broad Spectrum Antibiotics

• Effective against many bacteria

• Examples:

  • Tetracycline

  • Chloramphenicol

  • Ofloxacin

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✔ Chemotherapy

• Branch of chemistry dealing with treatment of diseases using drugs

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🔹 16.4 Chemicals in Food

✔ Food Preservatives

• Prevent spoilage by microbes

• Common preservatives:

  • Sodium benzoate

  • Sulphur dioxide

  • Vinegar

  • Sugar syrup

  • Salt

🔹 Use must be controlled as excess may be harmful

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✔ Artificial Sweetening Agents

• Sweet taste but no calories

• Used by diabetic patients

Examples:

• Saccharin

• Aspartame

• Alitame

🔹 Aspartame:

• Not suitable for cooking

• Decomposes at high temperature

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✔ Why Artificial Sweeteners Are Needed

• Reduce calorie intake

• Prevent tooth decay

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🔹 16.5 Cleansing Agents

✔ Soaps

• Sodium or potassium salts of fatty acids

• Prepared by saponification

• Do not work in hard water

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✔ Why Soaps Don’t Work in Hard Water

• Hard water contains Ca²⁺ and Mg²⁺ ions

• These form insoluble scum with soap

• Results in wastage of soap

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✔ Cleansing Action of Soap

• Soap molecule has:

  • Hydrophobic tail (oil loving)

  • Hydrophilic head (water loving)

• Forms micelles

• Oil gets trapped inside micelle and washed away

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🔹 16.6 Synthetic Detergents

✔ Why Detergents Are Better Than Soaps

• Work in hard water

• Work in acidic medium

• Calcium & magnesium salts are soluble

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✔ Types of Detergents

(A) Anionic Detergents

• Negative ion active part

• Examples:

  • Sodium lauryl sulphate

  • Sodium alkyl benzene sulphonate

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(B) Cationic Detergents

• Positive ion active part

• Quaternary ammonium salts

• Example:

  • Cetyltrimethyl ammonium chloride

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(C) Non-Ionic Detergents

• No charge

• Used in liquid detergents

• Functional groups:

  • Ether

  • Alcohol

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✔ Biodegradable vs Non-biodegradable Detergents

Biodegradable	Non-biodegradable
Straight chain	Branched chain
Decomposed by microbes	Cause water pollution
Example: SDS	Example: Branched ABS

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🔹 16.7 Antiseptics and Disinfectants

Antiseptics	Disinfectants
Used on living tissues	Used on non-living objects
Low concentration	High concentration
Example: tincture iodine	Example: phenol (1%)

🔹 Phenol:

• 0.2% → antiseptic

• 1% → disinfectant

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🔹 16.8 Important Chemicals

✔ Tincture of Iodine

• 2–3% iodine in alcohol

• Used as antiseptic

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✔ Dettol Constituents

• Chloroxylenol

• α-terpineol

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🔥 EXAM HOTSPOTS (VERY IMPORTANT)

✔ Drug–target interaction
✔ Antacids vs traditional bases
✔ Broad spectrum antibiotics
✔ Artificial sweeteners
✔ Soap cleansing mechanism
✔ Soaps vs detergents
✔ Biodegradable detergents
✔ Antiseptics vs disinfectants

✍️ Top 10 Short Question–Answers (Board Exam Oriented)

1. What are drugs?
   Drugs are chemical substances used to diagnose, prevent or treat diseases.

2. Why should drugs be taken in proper dose?
   Because in excess dose, a drug can act as a poison.

3. What are antacids?
   Drugs used to treat excess acidity in the stomach.

4. Why are ranitidine and cimetidine better antacids?
   Because they reduce acid secretion by blocking histamine receptors.

5. What are antibiotics?
   Drugs that kill or inhibit the growth of bacteria.

6. What are broad spectrum antibiotics?
   Antibiotics effective against a wide range of bacteria.

7. Why are artificial sweeteners used?
   To provide sweetness without adding calories.

8. Why do soaps not work in hard water?
   Because Ca²⁺ and Mg²⁺ ions form insoluble scum with soap.

9. What is the cleansing action of soap?
   Soap forms micelles that trap grease and wash it away.

10. What is the difference between antiseptics and disinfectants?
    Antiseptics are used on living tissues, disinfectants on non-living objects.

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📝 Long Answer Questions

1. Explain classification of drugs based on their therapeutic action.

Drugs are classified according to their effect on the body:

• Antacids:
  Used to treat acidity
  Examples: ranitidine, cimetidine

• Antihistamines:
  Used to control allergic reactions

• Antidepressants / Tranquilizers:
  Used to treat depression
  Examples: iproniazid, phenelzine

• Antibiotics:
  Kill or inhibit bacterial growth
  Examples: tetracycline, chloramphenicol

• Chemotherapy drugs:
  Used for treatment of diseases like cancer

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2. Explain cleansing action of soaps and why detergents are preferred.

Cleansing action of soap

• Soap molecule has:

  • Hydrophobic tail (oil loving)

  • Hydrophilic head (water loving)

• Soap molecules form micelles

• Grease is trapped inside micelle and washed away with water

Why detergents are preferred

• Work in hard water

• Do not form scum with Ca²⁺/Mg²⁺ ions

• Effective even in acidic medium

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3. Differentiate between soaps and detergents.

Property	Soaps	Detergents
Action in hard water	Do not work	Work
Reaction with Ca²⁺/Mg²⁺	Form scum	No scum
Medium	Not effective in acidic	Effective in acidic
Nature	Fatty acid salts	Sulphonates/sulphates

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❓ FAQs (Concept Clarity)

1. Why are drugs called chemicals of life?
   Because they interact with biochemical processes in the body.

2. Why are artificial sweeteners preferred by diabetic patients?
   Because they do not increase blood sugar level.

3. Why is aspartame not suitable for cooking?
   Because it decomposes at high temperature.

4. Why are biodegradable detergents preferred?
   Because they do not cause water pollution.

5. Why is phenol used in different concentrations?
   Low concentration acts as antiseptic, high concentration as disinfectant.

Chapter No.	Chapter Name	Visit
1	The Solid State	Visit
2	Solutions	Visit
3	Electrochemistry	Visit
4	Chemical Kinetics	Visit
5	Surface Chemistry	Visit
6	General Principles and Processes of Isolation of Elements	Visit
7	The p-Block Elements	Visit
8	The d and f Block Elements	Visit
9	Coordination Compounds	Visit
10	Haloalkanes and Haloarenes	Visit
11	Alcohols, Phenols and Ethers	Visit
12	Aldehydes, Ketones and Carboxylic Acids	Visit
13	Amines	Visit
14	Biomolecules	Visit
15	Polymers	Visit
16	Chemistry in Everyday Life	Visit

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