Solutions Question 55

Question: A 0.2 molal aqueous solution of a weak acid (HX) is 20% ionised. The freezing point of this solution is (Given Kf=1.86oC/m for water) [IIT 1995]

Options:

A) 0.31oC

B) 0.45oC

C) 0.53oC

D) 0.90oC

Show Answer

Answer:

Correct Answer: B

Solution:

ΔTf=molality×Kf×(1+α)

α=0.2 , Molality = 0.2, Kf=1.86

ΔTf=0.2×1.2×1.86=0.4464o Freezing point = 0.45oC .



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