25 mL of an aqueous solution of KCl was found to require 20 mL of 1 M AgNO₃ solution when titrated using K₂CrO₄ as indicator. Depression in freezing point of KCl solution with 100% ionisation will be-

Question

25 mL of an aqueous solution of KCl was found to require 20 mL of 1 M AgNO₃ solution when titrated using K₂CrO₄ as indicator. Depression in freezing point of KCl solution with 100% ionisation will be- (Kf = 2.0 K kg mol⁻¹ and molarity = molality)

Accepted Answer

Answer: 3.2 — Moles AgNO₃ = 1 × 0.020 = 0.020 mol Hence KCl in 25 mL = 0.020 mol Molarity = 0.020/0.025 = 0.8 M For complete ionisation: i = 2 ΔTf = iKfm = 2 × 2 × 0.8 = 3.2°C

Practice Chemistry Exams