Practice question
Question
A solution of 5 g of a solute (molar mass = 100 g/mol) in 200 g of water boils at 100.13°C at 1 atm. What is the van’t Hoff factor? ( Kb = 0.52 K kg mol⁻¹ )
Explanation
Moles = (5/100) = 0.05 . Molality = (0.05/0.2) = 0.25 mol/kg . Δ Tb = i · Kb · m . 0.13 = i × 0.52 × 0.25 , i = (0.13/0.52 × 0.25) = 1 .