Properties 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…

Question

Properties 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 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 of 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 answering 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

Accepted Answer

(B) 376.2 K

Properties such as boiling point, freezing point and vapour pressure of a pure solvent…

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