Topper's Short Notes 📝

Complete 10 Chapters | CBSE Class 12 Chemistry | Target 70/70

📊 Physical Chemistry

1 Solutions

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1. Henry's Law & Raoult's Law

Henry's Law: Solubility of gas in liquid ∝ partial pressure of gas. p = K_H * x. (Lower K_H = Higher solubility).
Raoult's Law: Partial vapour pressure of volatile component p₁ = p₁° * x₁.

2. Ideal vs Non-Ideal Solutions

Ideal: Obeys Raoult's Law. ΔH_mix = 0, ΔV_mix = 0. (e.g., Benzene + Toluene).
+ve Deviation: Weaker A-B interactions. V.P. increases. Minimum boiling azeotrope (Ethanol + Water).
-ve Deviation: Stronger A-B interactions. V.P. decreases. Maximum boiling azeotrope (HNO3 + Water).

3. Colligative Properties & Van't Hoff Factor (i)

Properties depending only on number of solute particles. To correct for association/dissociation, multiply by factor i.

1. RLVP: (P° - P)/P° = i * X_solute
2. Elevation in BP: ΔT_b = i * K_b * m
3. Depression in FP: ΔT_f = i * K_f * m
4. Osmotic Pressure: π = i * C * R * T

2 Electrochemistry

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1. Nernst Equation & Gibbs Free Energy

Used to calculate EMF of cell at non-standard conditions.

E_cell = E°_cell - (0.0591 / n) * log₁₀[Product]/[Reactant]
ΔG° = -n F E°_cell
ΔG° = -2.303 R T log(K_c)

2. Kohlrausch's Law

Limiting molar conductivity (Λ°_m) of an electrolyte is the sum of individual contributions of its cations and anions. Crucial for calculating Λ°_m of weak electrolytes (like CH3COOH).

3. Faraday's Laws of Electrolysis

First Law: Mass deposited w = Z * I * t.
Second Law: When same current passed through different electrolytes, w ∝ Equivalent weight.

4. Batteries & Fuel Cells

Lead Storage Battery: Discharging: Pb(s) + PbO2(s) + 2H2SO4(aq) → 2PbSO4(s) + 2H2O(l). Recharging inverses this.
H2-O2 Fuel Cell: Highly efficient, pollution-free. Water is the only byproduct.

3 Chemical Kinetics

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1. Order vs Molecularity

Order: Sum of powers of conc. terms in rate law. Exp. determined. Can be 0 or fractional.
Molecularity: Number of colliding species in an elementary step. Theoretical. Never 0.

2. Rate Constant (k) & Integrated Rate Laws

Zero Order: k = [R]₀ - [R] / t | t_1/2 = [R]₀ / 2k
First Order: k = (2.303/t) * log([R]₀/[R]) | t_1/2 = 0.693 / k

3. Arrhenius Equation (Temperature Dependence)

Rate constant doubles for every 10°C rise. Catalyst lowers activation energy (Ea) providing alternate path.

k = A * e^-Ea/RT
log(k₂/k₁) = (Ea / 2.303R) * [ (T₂ - T₁) / (T₁T₂) ]

⚛️ Inorganic Chemistry

4 d and f Block Elements

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1. General Properties of d-block (Transition Metals)

Variable Oxidation States: Due to involvement of both ns and (n-1)d electrons.
Colored Ions & Magnetism: Due to presence of unpaired d-electrons (d-d transition).
Magnetic moment μ = √(n(n+2)) BM.
Catalytic Properties: Ability to adopt multiple oxidation states and provide surface area.

2. Lanthanoid Contraction

Steady decrease in atomic/ionic radii of lanthanoids due to poor shielding of 4f electrons. Consequence: Radii of 4d & 5d series (e.g., Zr and Hf) become almost identical.

3. KMnO4 and K2Cr2O7

Strong oxidizing agents. Learn Ionic Equations:

Acidic KMnO4: MnO4⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H2O (Colorless)
Acidic K2Cr2O7: Cr2O7²⁻ + 14H⁺ + 6e⁻ → 2Cr³⁺ + 7H2O (Green)

5 Coordination Compounds

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1. Valence Bond Theory (VBT)

Strong Field Ligands (CO, CN-, NH3): Pair up electrons. Usually form Inner orbital complexes (d²sp³) - Diamagnetic.
Weak Field Ligands (Halogens, H2O): Do not pair. Form Outer orbital complexes (sp³d²) - Paramagnetic.

2. Crystal Field Theory (CFT)

Ligands split the degenerate d-orbitals into t2g (lower) and eg (higher) sets in octahedral field.
If Δo > P (Strong ligand): 4th electron goes to t2g (low spin, pairing occurs).
If Δo < P (Weak ligand): 4th electron goes to eg (high spin).

3. Isomerism

Linkage: Ambidentate ligands (NO2 vs ONO).
Optical: Non-superimposable mirror images. Common in [M(en)3]³⁺ types.
Geometrical: Cis (adjacent) vs Trans (opposite). Forms in square planar [Ma2b2] or octahedral [Ma4b2].

🧪 Organic Chemistry

6 Haloalkanes and Haloarenes

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1. SN1 vs SN2 Mechanisms

SN1: Two steps. Carbocation intermediate. Reactivity order: 3° > 2° > 1°. Stereochem: Racemization. Favored by polar protic solvents.
SN2: Single step. Transition state. Reactivity order: 1° > 2° > 3° (Steric hindrance). Stereochem: Inversion of configuration (Walden Inversion).

2. Key Name Reactions

Sandmeyer: Benzenediazonium chloride + CuCl/HCl → Chlorobenzene.
Finkelstein: R-X + NaI (Dry Acetone) → R-I + NaX (Halogen exchange to form Iodides).
Swarts: R-X + AgF → R-F (Formation of Fluorides).
Wurtz-Fittig & Fittig: Ar-X + R-X + 2Na (Ether) → Ar-R (Alkyl arene) / Ar-X + Ar-X → Ar-Ar (Biphenyl).

3. Addition to Alkenes

Markovnikov's rule: Neg part of reagent (like X⁻ from HX) attaches to C with less Hydrogen.
Anti-Markovnikov (Peroxide effect / Kharasch): Only with HBr + Peroxide. Br attaches to C with more Hydrogen.

7 Alcohols, Phenols, and Ethers

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1. Acidic Character (Phenol vs Alcohol)

Phenol is more acidic than alcohols due to resonance stabilization of phenoxide ion.
- EWG (like -NO2) increases acidity (e.g., Picric acid).
- ERG (like -CH3) decreases acidity.

2. Preparation of Alcohols

Acid Catalyzed Hydration: Markovnikov addition of H2O. Rearrangement possible.
Hydroboration-Oxidation (HBO): Anti-Markovnikov addition of H2O. No rearrangement. Uses B2H6, then H2O2/OH⁻.

3. Mighty Name Reactions & Tests

Reimer-Tiemann: Phenol + CHCl3 + aq.NaOH → Salicylaldehyde.
Kolbe's Rxn: Phenol + CO2 + NaOH → Salicylic acid.
Williamson Synthesis: RONa + R'X → R-O-R'. R'X must be PRIMARY (1°) to avoid elimination (alkene).
Lucas Test (ZnCl2/HCl): Distinguishes 1°, 2°, 3° alcohols. 3° gives immediate turbidity.

8 Aldehydes, Ketones, Carboxylic Acids

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1. Test for Aldehydes vs Ketones

Tollens' Test (Silver Mirror): Aldehydes (both aliphatic & aromatic) give +ve test. Ketones do not.
Fehling's Test: Red ppt. Aliphatic aldehydes give +ve. (Aromatic aldehydes and Ketones do not).
Iodoform Test (NaOI): For compounds containing CH3-C=O or CH3-CH(OH)- group. Forms yellow ppt of CHI3.

2. Alpha-Hydrogen Reactions (VVI)

Aldol Condensation: Ald/Ket WITH alpha-H (e.g., Acetaldehyde). Dilute NaOH. Forms β-hydroxy aldehyde → heated to α,β-unsaturated carbonyl.
Cannizzaro Reaction: Aldehydes WITHOUT alpha-H (e.g., HCHO, Benzaldehyde). Conc. NaOH. Self oxidation-reduction (disproportionation) into alcohol and acid salt.

3. Name Reactions for Synthesis & Reduction

Rosenmund: Acid chloride + H2/Pd-BaSO4 → Aldehyde.
Clemmensen: C=O + Zn-Hg/HCl → CH2 (Alkanes).
Wolff-Kishner: C=O + NH2NH2 / KOH, Glycol → CH2.
HVZ Reaction: Carboxylic acid (with alpha-H) + X2/Red P → Alpha-halo carboxylic acid.

9 Amines

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1. Basic Character of Amines

Gas phase: 3° > 2° > 1° > NH3 (Due to +I effect of alkyl groups).
Aqueous phase (Methyl -CH3): 2° > 1° > 3° > NH3.
Aqueous phase (Ethyl -C2H5): 2° > 3° > 1° > NH3 (Calculated based on +I, solvation, and steric hindrance).
Aniline is WEAKER base than NH3 due to resonance of lone pair with benzene ring.

2. Essential Name Rxns & Tests

Hoffmann Bromamide Degradation: Amide + Br2 + 4NaOH → 1° Amine (with ONE carbon less). Step-down rxn.
Gabriel Phthalimide: For pure 1° aliphatic amines ONLY. Cannot prepare aniline (Ar-X doesn't do SN2).
Carbylamine Test (Isocyanide test): ONLY 1° amines (aliphatic/aromatic) + CHCl3 + KOH → Foul-smelling Isocyanide.
Hinsberg Test: Uses Benzene sulphonyl chloride. 1° amine product is soluble in alkali, 2° is insoluble, 3° doesn't react.

10 Biomolecules

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1. Carbohydrates

Reducing Sugars: Contain free aldehyde/ketonic group (reduce Tollens/Fehling). e.g., Glucose, Fructose, Maltose, Lactose. (Sucrose is NON-reducing).
Glucose Structure: Known to have straight 6-C chain (HI/red P), carbonyl is aldehyde (Br2 water oxidation).
Anomers & Mutarotation: Alpha and Beta D-glucose are anomers (differ at C1). Slow change of optical rotation towards equilibrium is mutarotation.

2. Proteins

Unit: Alpha-amino acids joined by Peptide linkage (-CO-NH-).
Structure: 1° (Sequence of amino acids), 2° (Alpha-helix, beta-pleated sheet via H-bonds), 3° (3D folding), 4° (Subunit assembly).
Denaturation: Loss of biological activity due to heat/pH change. 2° & 3° structures destroyed, 1° remains intact. (e.g., Boiling egg, curdling milk).

3. Nucleic Acids & Vitamins

DNA vs RNA: DNA has Deoxyribose, Thymine. RNA has Ribose, Uracil (U instead of T). Double helix vs single strand.
Fat Soluble Vitamins: A, D, E, K. Subcutaneous fat storage.
Water Soluble: B, C. Excreted in urine (must be supplied in diet daily, exception B12).