Chemistry - Liquid Solution Question with Solution | TestHub

ChemistryLiquid SolutionAbnormal Colligatiove PropertiesHard2 minPYQ_2018
ChemistryHardnumerical

The plot given below shows P-T curves (where, P is the pressure and T is the temperature) for two solvents X and Y and isomolal solutions of NaCl in these solvents. NaCl is completely dissociates in both the solvents.

On the addition of equal number of moles of a non-volatile solute S in equal amount (in kg) of these solvents, the elevation of boiling point of solvent X is three times that of solvent Y. The solute S is known to undergo dimerization in these solvents. If the degree of dimerization is 0.7 in the solvent Y, the degree of dimerization in the solvent X is _______.

Answer:
0.05
Solution:

From the graph:
For the solvent X,    

Tbx=2
Tbx=mNaCl×Kbx  ...i
For the solvent Y,   

Tby=1
Tby=mNaCl×Kby  ...ii
From the equations (i) and (ii),
 KbxKby=2
For the solute S,

i=1-α2
Tbxs=1-α12Kbx
Tbys=1-α22Kby
Given: 

Tbxs=3Tbys
1-α12Kbx=3×1-α12×kby
21-α12=31-α22
α2=0.7
So, α=0.05

Subject:ChemistryTopic:Liquid SolutionSubtopic:Abnormal Colligatiove Properties
2mℹ️ Source: PYQ_2018

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