Properties such as boiling point, freezing point and vapour, pressure of a pure solvent change Propeties such as boiling point, freezing point and vapour, pressure of a pure solvent change when solute molecules are added to get homogeneous solution. These are called colligative properties. Applications of colligative properties are very useful in day-to-day life. One of its examples is the use of ethylene glycol and water mixture as anti-freezing liquid in the radiator of automobiles.
A solution M is prepared by mixing athanol 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 of ethanol `(K_(f)^("ethanol"))=2.0 K kg "mol"^(-1)`
Boiling point elevation constant of water `(K_(b)^("water"))=0.52 kg "mol"^(-1)`
Boiling point elevation constant of ethanol `(K_(b)^("ethanol"))=1.2 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
tandard boiling point of ethanol =351.5 K
Vapour pressure of pure water =32.8 mmHg
Vapour presure of pure ethanol =40g Hg
Molecular weight of water `=18 g"mol"^(-1)`
Molecules weight of ethanol `=46 g "mol"^(-1)`
In answering the following questions, consider the solutions to be ideal dilute solutions and solutes to be non-volatile and non-dissociative.
when solute molecules are added to get homogeneous solution. These are called colligative properties. Applications of colligative properties are very useful in day-to-day life. One of its examples is the use of ethylene glycol and water mixture as anti-freezing liquid in the radiator of automobiles.
A solution M is prepared by mixing athanol 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 of ethanol `(K_(f)^("ethanol"))=2.0 K kg "mol"^(-1)`
Boiling point elevation constant of water `(K_(b)^("water"))=0.52 kg "mol"^(-1)`
Boiling point elevation constant of ethanol `(K_(b)^("ethanol"))=1.2 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
tandard boiling point of ethanol =351.5 K
Vapour pressure of pure water =32.8 mmHg
Vapour presure of pure ethanol =40g Hg
Molecular weight of water `=18 g"mol"^(-1)`
Molecules weight of ethanol `=46 g "mol"^(-1)`
In answering 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

Options

A. `268.7 K`
B. `268.5 K`
C. `234.2 K`
D. `150.9 K`

Answer

D

Explanation

`DeltaT_(f)=K_(t)xxm`
`2xx(0.1)/(0.9xx46)xx100=4.83K`
Freezing point of solution `M=155.7-4.83=150.87 K=150.9K`