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Question: Answered & Verified by Expert
The freezing point of a 0.08 molal aqueous solution of NaHSO4 is -0.372°C . The dissociation constant for the following reaction is ( Kf for H2O=1.86 K kg mol-1 )

HSO4-H++SO42-
ChemistrySolutionsJEE Main
Options:
  • A 0.04
  • B 0.02
  • C 0.01
  • D 0.2
Solution:
1114 Upvotes Verified Answer
The correct answer is: 0.04
NaHSO4Na+0.08+HSO4-0.08

HSO4-0.08(1-α)H+0.08α+SO42-0.08α

i=0.08+0.081-α+0.08α+0.08α0.08=2+α

ΔT=i×Kf×m

0.372=i×1.86×0.08

i=2.5

So 2+α=2.5

α=0.5

Dissociation constant, K=0.08α×0.08α0.081-α

=0.08×0.5×0.08×0.50.08×0.5=0.04

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