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A solution M is prepared by mixing ethan...

A solution `M` is prepared by mixing ethanol and water. The mole fraction of ethanol in the mixture is `0.9`
Given: Freezing point depression constant of water
`(K_(f)^(water)=1.86 K kg mol^(-1))`
Freezing point depression constant to ethanol
`(K_(f)^(ethanol))=2.0 K kg mol^(-1))`
Boiling point elevation constant of water
`(K_(b)^(water))=0.52 K kg mol^(-1))`
Boiling point elevation constant of ethanol
`(K_(b)^(ethanol))=1.2 K kg mol^(-1))`
Standard freezing point of water = `273 K `
Standard freezing point of ethanol = `155.7 K `
Standard boiling point of water = `373 K `
Standard boiling point of ethanol = `351.5 K `
Vapour pressure of pure water =`32.8 mm Hg`
Vapour pressure of pure ethanol =`40 mm Hg`
Molecular weight of water =`18 g mol^(-1)`
Molecular weight of ethanol =`46 g mol^(-1)`
In anwering the following questions consider the solutions to be ideal dilute solutions and solutes to be non-volatile and non-dissociative.
Water is added to the solution `M` such that the mole fraction of water in the solution becomes `0.9`. The boiling point of this solution is

A

`380.4 K`

B

`376.2 K`

C

`375.5 K`

D

`354.7 K`

Text Solution

Verified by Experts

The correct Answer is:
B
`chi_("Ethanol")=0.1`
` chi_("water")=0.9`
`("Solvent" =-B)`
`("Solvent" =-A)`
`DeltaT_(b)=K_(b) .m=K_(b) . (chi_(B))/(1-chi_(B)) xx (1000)/(Mw_(A))`
`=0.52 xx 0.1/0.9 xx 1000/18=3.2 K`
`T_(b)=T_(b)^(@)-DeltaT_(b)=373 + 3.2 =376.2 K`
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A solution M is prepared by mixing ethanol and water. The mole fraction of ethanol in the mixture is 0.9 Given: Freezing point depression constant of water (K_(f)^(water)=1.86 K kg mol^(-1)) Freezing point depression constant to ethanol (K_(f)^(ethanol))=2.0 K kg mol^(-1)) Boiling point elevation constant of water (K_(b)^(water))=0.52 K kg mol^(-1)) Boiling point elevation constant of ethanol (K_(b)^(ethanol))=1.2 K kg mol^(-1)) Standard freezing point of water = 273 K Standard freezing point of ethanol = 155.7 K Standard boiling point of water = 373 K Standard boiling point of ethanol = 351.5 K Vapour pressure of pure water = 32.8 mm Hg Vapour pressure of pure ethanol = 40 mm Hg Molecular weight of water = 18 g mol^(-1) Molecular weight of ethanol = 46 g mol^(-1) In anwering the following questions consider the solutions to be ideal dilute solutions and solutes to be non-volatile and non-dissociative. The freezing point of the solution M is

A solution M is prepared by mixing ethanol and water. The mole fraction of ethanol in the mixture is 0.9 Given: Freezing point depression constant of water (K_(f)^(water)=1.86 K kg mol^(-1)) Freezing point depression constant to ethanol (K_(f)^(ethanol))=2.0 K kg mol^(-1)) Boiling point elevation constant of water (K_(b)^(water))=0.52 K kg mol^(-1)) Boiling point elevation constant of ethanol (K_(b)^(ethanol))=1.2 K kg mol^(-1)) Standard freezing point of water = 273 K Standard freezing point of ethanol = 155.7 K Standard boiling point of water = 373 K Standard boiling point of ethanol = 351.5 K Vapour pressure of pure water = 32.8 mm Hg Vapour pressure of pure ethanol = 40 mm Hg Molecular weight of water = 18 g mol^(-1) Molecular weight of ethanol = 46 g mol^(-1) In anwering the following questions consider the solutions to be ideal dilute solutions and solutes to be non-volatile and non-dissociative. The vapour pressure of the solution M is

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