Question

0.3 g of acetic acid (M = 60 g mol⁻¹) dissolved in 30 g of benzene shows a depression in freezing point equal to 0.45°C. Calculate the percentage association of acid if it forms a dimer in the solution. (Given: Kf for benzene = 5.12 K kg mol⁻¹)

If benzoic acid (M = 122 g mol⁻¹) is associated into a dimer when dissolved in benzene and the osmotic pressure of a solution of 6·1 g of benzoic acid in 100 mL benzene is 6·5 atm at 27°C, then what is the percentage association of benzoic acid ? (Given : R = 0·0821 L atm K⁻¹ mol⁻¹)