If molar conductance at infinite dilution for CH ₃ COO ^- and H ^+ ions are 50 S cm ^2 mol ⁻¹ and 350 S cm ^2 mol ⁻¹ respectively, molar conductivity of 5 10⁻² M CH ₃ COOH is 20 S cm ^2 mol ⁻¹ . What is the hydrogen ion concentration in mol/dm ^3 of CH ₃ COOH ?

Step-by-step solution

Molar conductivity at infinite dilution for CH ₃ COOH is given by Kohlrausch's law: _m^ = ^ ( CH ₃ COO ^-) + ^ ( H ^+) _m^ = 50 + 350 = 400 S cm ^2 mol ⁻¹ Degree of dissociation is: = _m _m^ = 20 400 = 0.05 Hydrogen ion concentration is: [ H ^+] = C = (5 10⁻²) 0.05 = 2.5 10⁻³ mol/dm ^3 Answer: 2.5 10⁻³