IIT JEE Advanced 2006 Paper 1

The dimerization reaction of phenol is
2C6H5OH ⇌ (C6H5OH)2

Initial‌concentration	C	0
After‌dimerization	C−Cα	Cα 2

Here, C is the concentration of phenol:
C =

75.2

Mol.wt

=

75.2

94

= 0.8
and α is the degree of dissociation. Then
i = C - Cα + Cα/2 =

C(2−α)

2

Freezing point depression is given by
ΔTf = Kf×i
7 = 14 × 0.8 × (2−

α

2

)
α = 0.75 = 75%