Class 12 Chemistry Detailed Revision Notes:
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Class 12 Chemistry – Complete Board Exam Revision Notes
(Highly Concise, Exam-Oriented, 70-Mark Focused)
Exam Pattern & Weightage (70 Marks)
| Section | Marks |
|---|---|
| Physical Chemistry | 23 |
| Inorganic Chemistry | 14 |
| Organic Chemistry | 33 |
| Total | 70 |
Revision Strategy
- 5-day rapid revision + daily PDF daily repeat
- Focus: Revision > New learning
- Must solve: PYQs + Top 30 questions + Case-based + MCQs.Chemistry Detailed Revision Notes
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PHYSICAL CHEMISTRY (23 Marks)
1. Solutions
| Concept | Key Point |
|---|---|
| Temperature-dependent units | Molarity, % V/V, % W/V |
| Temperature-independent units | Molality, Mole fraction, % W/W |
| Solid in Liquid | Solubility ↑ with T, Pressure → no effect |
| Gas in Liquid | Solubility ↓ with T, ↑ with P (Henry’s Law) |
| Henry’s Law | P = KH × X → Higher KH = Lower solubility |
| Raoult’s Law | P = P°A XA + P°B XB |
| Positive deviation | Weak A–B → ΔHmix > 0 → Minimum boiling azeotrope |
| Negative deviation | Strong A–B → ΔHmix < 0 → Maximum boiling azeotrope |
| Colligative properties | ↓VP, ↑BP, ↓FP, Osmotic pressure ∝ i × molality |
| Van’t Hoff factor (i) | >1 → dissociation, <1 → association |
2. Electrochemistry
| Topic | Remember |
|---|---|
| Cell notation | E°cell = E°cathode – E°anode (reduction potential) |
| Nernst equation (298 K) | Ecell = E°cell – (0.059/n) log Q |
| ΔG° | = –nFE°cell → Spontaneous if E°cell > 0 |
| Conductivity (κ) | ↓ on dilution |
| Molar conductivity (Λm) | ↑ on dilution (sharp ↑ in weak electrolytes) |
| Kohlrausch Law | Λ°m (strong) = ν+ λ°+ + ν– λ°– |
| Electrolytic products | Cathode: higher SRP highest wins Anode: Halides (conc.) > OH⁻ (overpotential) |
3. Chemical Kinetics
| Order | Rate law | t½ | Unit of k |
|---|---|---|---|
| 0 | rate = k | t½ ∝ [A]₀ | mol L⁻¹ s⁻¹ |
| 1 | rate = k[A] | t½ = 0.693/k (constant) | s⁻¹ |
| 2 | rate = k[A]² | t½ ∝ 1/[A]₀ | L mol⁻¹ s⁻¹ |
- Arrhenius: k = A e^(–Ea/RT) → Rate ↑ exponentially with T
- Catalyst lowers Ea, no change in ΔH or Keq.Chemistry Detailed Revision Notes
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INORGANIC CHEMISTRY (14 Marks)
1. d- & f-Block Elements
| Property | Reason |
|---|---|
| High MP | Strong metallic bond due to unpaired d-electrons |
| Variable oxidation states | Close energy of (n–1)d & ns orbitals |
| Coloured ions | d-d transition (unpaired electrons) |
| Zn, Cd, Hg | Non-transition (d¹⁰ configuration) |
| Cr, Cu anomalies | Cr: [Ar] 3d⁵ 4s¹ ; Cu: [Ar] 3d¹⁰ 4s¹ (half/full filled stability) |
| Lanthanoid contraction | Poor shielding by 4f → atomic size 4d ≈ 5d series |
| KMnO₄, K₂Cr₂O₇ colour | Charge transfer (not d-d) |
2. Coordination Compounds
| Theory | Key Points |
|---|---|
| VBT | Strong field ligand → pairing → inner orbital (d²sp³ low spin) Weak field → sp³d² high spin |
| CFT | Octahedral splitting: t₂g < eg Δo > P → low spin Δo < P → high spin |
| Isomerism | Structural: Linkage, Ionisation, Hydrate, Coordination Stereo: Geometrical (cis/trans, fac/mer), Optical |
Important: [Ma₄b₂] → cis/trans ; [Ma₃b₃] → fac/mer ; Tetrahedral → no geometrical isomerism
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ORGANIC CHEMISTRY (33 Marks)
Reaction Preference Table
| Substrate | Reagent/Condition | Major Product / Reaction |
|---|---|---|
| 1° Alcohol | 413 K | Ether (SN2) |
| 1° Alcohol | 443 K | Alkene (E2) |
| 3° Alkyl halide | Polar protic (H₂O, alcohol) | SN1 + E1 (racemisation + rearrangement possible) |
| 1° Alkyl halide | Polar aprotic (DMF, acetone) | SN2 (100% inversion) |
| Phenol | – | More acidic than alcohol (resonance in phenoxide) |
| Aniline | – | Weak base (lone pair delocalised) |
Distinguishing Tests (High Weightage)
| Test | Positive for | Observation |
|---|---|---|
| Tollen’s | All aldehydes + HCOOH | Silver mirror |
| Fehling’s | Only aliphatic aldehydes | Red ppt Cu₂O |
| Iodoform | CH₃–CO– or CH₃–CH(OH)– or acetaldehyde, ethanol | Yellow ppt CHI₃ |
| Lucas (ZnCl₂/HCl) | 3° > 2° > 1° alcohol | Turbidity time |
| Carbylamine | Only 1° amines | Foul smell |
| Hinsberg | 1° → soluble in alkali, 2° → insoluble, 3° → no rxn | – |
Name Reactions (Must Know Mechanism)
- Cannizzaro (no α-H aldehydes)
- Aldol / Cross Aldol
- Clemmensen & Wolff-Kishner
- HVZ
- Reimer-Tiemann
- Williamson ether synthesis
- Sandmeyer / Gattermann
- Finkelstein
- Swarts
- Wurtz / Wurtz-Fittig
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BIOMOLECULES (7 Marks)
Carbohydrates
- Glucose open chain: 5 –OH + 1 –CHO (proved by penta-acetate + HI → n-hexane)
- Cyclic: Pyranose form dominant → α & β anomers
- Sucrose: Non-reducing, invert sugar (α1→β2 linkage)
- Maltose/Lactose: Reducing (free anomeric OH).Chemistry Detailed Revision Notes
Proteins
Peptide bond → Primary → Secondary (α-helix/β-sheet) → Tertiary → Quaternary
Denaturation: Loses 2° & 3° structure, primary remains
Nucleic Acids
| Feature | DNA | RNA |
|---|---|---|
| Sugar | Deoxyribose | Ribose |
| Bases | A, T, G, C | A, U, G, C |
| Structure | Double helix | Single strand |
| Linkage | Phosphodiester | Phosphodiester |
Vitamins
Vitamins Quick Table
| Type | Vitamins | Deficiency Disease |
|---|---|---|
| Fat soluble | A, D, E, K | Night blindness, Rickets |
| Water soluble | B-complex, C | Beri-beri, Scurvy |
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Final Tip: Revise this sheet daily + solve at least 5 numericals from Solutions, Electrochemistry & Kinetics + 10 organic conversions daily.
All the best – score 70/70!Chemistry Detailed Revision Notes