Ch 2 covers solutions — types, concentration expressions, Raoult's law, ideal/non-ideal behaviour, colligative properties (vapour pressure lowering, boiling point elevation, freezing point depression, osmotic pressure), and abnormal molar masses.
Expressions: molarity, molality, mole fraction, ppm. Raoult's law: partial vapour pressure = mole fraction × vapour pressure of pure component. Ideal solutions obey Raoult's law (ΔH_mix = 0, ΔV_mix = 0). Non-ideal: positive deviation (A-B weaker than A-A, B-B; e.g. ethanol-acetone) and negative deviation (A-B stronger; e.g. CHCl₃-acetone).
Depend only on number of solute particles, not nature. ΔTb = iKb·m (boiling point elevation). ΔTf = iKf·m (freezing point depression). π = iCRT (osmotic pressure). Van't Hoff factor i corrects for association/dissociation.
Download: https://ncert.nic.in/textbook/pdf/lech102.pdf | Part I: https://ncert.nic.in/textbook/pdf/lech1ps.zip
The Van't Hoff factor (i) accounts for the actual number of particles a solute produces in solution. For non-electrolytes, i ≈ 1. For strong electrolytes like NaCl, i ≈ 2 (Na⁺ + Cl⁻). For weak electrolytes, 1 < i < expected value. For association (e.g. benzoic acid in benzene), i < 1.
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