SATHEE: Solutions Question 336

Solutions Question 336

Question: A solution of urea (mol. mass $56 g m o l^{- 1}$ ) boils at $100.18^{\circ} C$ at the atmospheric pressure. If $K_{f}$ and $K_{b}$ for water are 1.86 and $0.512 K k g m o l^{- 1}$ respectively, the above solution will freeze at

Options:

A) $0.654^{\circ} C$

B) $- 0.654^{\circ} C$

C) $6.54^{\circ} C$

D) $- 6.54^{\circ} C$

Show Answer

Answer:

Correct Answer: B

Solution:

As $Δ T_{f} = K_{f} m$

$Δ T_{b} = K_{b} . m$ Hence, we have $m = \frac{Δ T_{f}}{K_{f}} = \frac{Δ T_{b}}{K_{b}}$ or $Δ T_{f} = Δ T_{b} \frac{K_{f}}{K_{b}}$

$[Δ T_{b} = 100.18 - 100 = 0.18^{\circ} C]$

$= 0.18 \times \frac{1.86}{0.512} = 0.654^{\circ} C$ As the freezing point of pure water is $0^{\circ} C,$

$Δ T_{f} = 0 - T_{f}$

$0.654 = 0 - T_{f}$
$∴ T_{f} = - 0.654$ Thus the freezing point of solution will be $- 0.654^{\circ} C .$

Solutions Question 336

Question: A solution of urea (mol. mass $56 g m o l^{- 1}$ ) boils at $100.18^{\circ} C$ at the atmospheric pressure. If $K_{f}$ and $K_{b}$ for water are 1.86 and $0.512 K k g m o l^{- 1}$ respectively, the above solution will freeze at

Options:

Answer:

Solution:

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Solutions Question 336

Question: A solution of urea (mol. mass 56gmol−1 ) boils at 100.18∘C at the atmospheric pressure. If Kf and Kb for water are 1.86 and 0.512Kkgmol−1 respectively, the above solution will freeze at

Options:

Answer:

Solution:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

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Question: A solution of urea (mol. mass $56 g m o l^{- 1}$ ) boils at $100.18^{\circ} C$ at the atmospheric pressure. If $K_{f}$ and $K_{b}$ for water are 1.86 and $0.512 K k g m o l^{- 1}$ respectively, the above solution will freeze at