Rishi Sharma
Last Activity: 4 Years ago
Dear Student,
Please find below the solution to your problem.
Phenol dimerises in the solvent (organic) as :
2C6H5OH ⇌ (C6H5OH)2
1 mol 0 mol (Initial)
1 - ∝ mol ∝/2 mol (Equilibrium)
Van’t Hoff factor, i = 1 - ∝ + ∝/2 = 1 - ∝/2
Where ∝ is the degree of dimerization.
∆Tf(obs) = Kf * molality * i
Or 7 = 14 * m * (1 - ∝/2)
In the given problem, amount of the solvent used to dissolved 75.2 g of phenol is not mentioned. Hence molality m, can not be calculated and so also the value of ∝.
If amount of solution is presumed to be 1 kg (= 100g) then,
M = 75.2/94 = 0.8 (mol. mass of phenol = 9.4)
And 7 = 14 * 75.2/94 * (1 - ∝/2)
Or ∝ = 0.75 = 75%
Thanks and Regards