Class 12 Chemistry: Complete Revision Notes

Class 12 Chemistry: Complete Revision Notes Comprehensive Short Notes for Board Exams & Competitive Entrance 1. Solutions • Raoult's Law: For a solution of volatile liquids, the partial vapor pressure of each component is directly proportional to its mole fraction. p1 = p1°x1 • Ideal Solutions: Obey Raoult's law over entire concentration range. ΔHmix = 0, ΔVmix = 0. • Colligative Properties: Depend only on number of solute particles. ◦ Relative lowering of vapor pressure ◦ Elevation of boiling point: ΔTb = Kbm ◦ Depression of freezing point: ΔTf = Kfm ◦ Osmotic Pressure: π = CRT • van't Hoff Factor (i): i = Observed Colligative Property / Calculated Colligative Property. 2. Electrochemistry • Nernst Equation: E = E° - (0.059/n) log [Products]/[Reactants] at 298K. • Kohlrausch's Law: Limiting molar conductivity of an electrolyte is the sum of the individual contributions of the anions and cations. • Faraday's First Law: w = ZIt. • Gibbs Energy: ΔG° = -nFE°cell. Page 1 3. Chemical Kinetics • Rate Law: Rate = k[A]x[B]y. Order = x + y. • Integrated Rate Equations: ◦ Zero Order: [R] = -kt + [R]0 ◦ First Order: k = (2.303/t) log([R]0/[R]) • Arrhenius Equation: k = Ae-Ea/RT. 4. d- and f- Block Elements • Transition Elements: Partially filled d-orbitals. Exhibit variable oxidation states, form colored ions, and act as catalysts. • Lanthanoid Contraction: Steady decrease in atomic and ionic radii with increase in atomic number due to poor shielding of 4f electrons. • Potassium Dichromate (K2Cr2O7): Strong oxidizing agent in acidic medium. 5. Coordination Compounds • Werner's Theory: Primary valence (ionizable, oxidation state) and Secondary valence (non-ionizable, coordination number). • VBT: Explains hybridization (sp3, dsp2, sp3d2, d2sp3) and magnetic properties. • Crystal Field Theory (CFT): Splitting of d-orbitals in octahedral (Δo) and tetrahedral (Δt) fields. Page 2 6. Haloalkanes and Haloarenes • SN2: Single step, inversion of configuration, reactivity: 1° > 2° > 3°. • SN1: Two steps, carbocation intermediate, racemization, reactivity: 3° > 2° > 1°. • Aryl Halides: Less reactive towards nucleophilic substitution due to resonance and sp2 hybridization of C. 7. Alcohols, Phenols and Ethers • Acidity: Phenols are more acidic than alcohols due to resonance stabilization of phenoxide ion. • Lucas Test: Distinguishes 1°, 2°, 3° alcohols (3° gives turbidity immediately). • Reimer-Tiemann Reaction: Phenol + Chloroform + NaOH → Salicylaldehyde. • Williamson Synthesis: R-X + R'-ONa → R-O-R' + NaX. 8. Aldehydes, Ketones and Carboxylic Acids • Nucleophilic Addition: Characteristic reaction of carbonyl groups. • Aldol Condensation: Aldehydes/Ketones with α-hydrogen in presence of dilute alkali. • Cannizzaro Reaction: Aldehydes with NO α-hydrogen in presence of conc. alkali. • HVZ Reaction: Carboxylic acids with α-hydrogen reacted with X2/Red P. Page 3 9. Amines • Basicity: Aliphatic amines are stronger bases than ammonia. Order in aqueous: 2° > 3° > 1° (for methyl). • Hinsberg's Test: Distinguishes 1°, 2°, 3° amines using benzene sulphonyl chloride. • Hoffmann Bromamide Degradation: RCONH2 + Br2 + 4NaOH → RNH2 + Na2CO3 + 2NaBr + 2H2O. 10. Biomolecules • Carbohydrates: Monosaccharides (Glucose, Fructose), Disaccharides (Sucrose, Maltose). • Proteins: Polymers of α-amino acids linked by peptide bonds. Denaturation destroys 2° and 3° structures. • Nucleic Acids: DNA (double helix, ATGC) and RNA (single strand, AUGC). Page 4