Ch 6 covers chemical equilibrium (Kc, Kp, Le Chatelier's principle) and ionic equilibrium (acids/bases, pH, buffer solutions, solubility product) — crucial for understanding reaction behaviour.
Dynamic equilibrium: forward and reverse rates equal. Equilibrium constant Kc = [C]ᶜ[D]ᵈ/[A]ᵃ[B]ᵇ. Kp = Kc(RT)^Δn (for gases). Le Chatelier's principle: if a system at equilibrium is disturbed, it shifts to oppose the change. Increase concentration → shifts away; increase pressure → shifts to fewer moles of gas; increase temperature → shifts in endothermic direction.
Strong acids/bases: fully dissociate. Weak acids/bases: partially dissociate (Ka, Kb). pH = −log[H⁺]. Kw = Ka × Kb = 10⁻¹⁴ at 25°C. Buffer solutions: weak acid + conjugate base (or vice versa), resist pH changes. Henderson: pH = pKa + log([salt]/[acid]). Common ion effect: adding a common ion suppresses dissociation. Solubility product Ksp: for sparingly soluble salts.
Download: https://ncert.nic.in/textbook/pdf/kech106.pdf | Part I: https://ncert.nic.in/textbook/pdf/kech1ps.zip
A buffer resists pH changes on addition of small amounts of acid or base. Acidic buffer: weak acid + its salt (CH₃COOH + CH₃COONa). When acid is added, the conjugate base (CH₃COO⁻) neutralises it. When base is added, the weak acid neutralises it. Blood is buffered at pH 7.4 by the H₂CO₃/HCO₃⁻ system.
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