Give all the relations between van't hoff factor with depression in freezing point, relation with elevation in boiling point, boiling point and freezing point of the solution and with the vapour pressure ?

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Q. Assertion :A non volatile solute is mixed in a solution then elevation in boiling point and depression in freezing point both are

2 K

. Reason: Elevation in boiling point and depression in freezing point both depend on melting point of non-volatile solute.

Q. Elevation in the boiling point for 1 molal solution of glucose is 2K. The depression in the freezing point of 2 molal solutions of glucose in the same solvent is 2K. The relation between

K_{b}

and

K_{f}

State True or False.

For the same solution, the elevation in boiling point has higher values than depression in freezing point .

Question 31
Isotonic solutions must have the same .......... .
(a) solute (b) density
(c) elevation in boiling point (d) depression in freezing point

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

$(K_{f}^{w a t e r}) = 1.86 K k g m o l^{- 1}$

Freezing point depression constant of ethanol

$(K_{b}^{w a t e r}) = 2.0 K k g m o l^{- 1}$

Boiling point elevation constant of water

$(K_{b}^{w a t e r}) = 0.52 K k g m o l^{- 1}$

Boiling point elevation constant of ethanol

$(K_{b}^{e t h a n o l}) = 1.2 K k g m o l^{- 1}$

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 = 351.5K

Vapour pressure of pure water = 32.8 mm Hg

Vapour pressure of pure ethanol = 40 mm Hg

Molecular weight of water $= 18 g m o l^{- 1}$

Molecular weight of ethanol $= 46 g m o l^{- 1}$

In answering 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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