Raoult's Law

IMPORTANT

Raoult's Law: Overview

This topic covers concepts, such as, Raoult's Law, Raoult's Law for an Ideal Solution of Two Liquid Components, Calculation of Composition of Liquid and Vapour in a Solution & Temperature versus Composition Phase Diagram for an Ideal Solution etc.

Important Questions on Raoult's Law

HARD
IMPORTANT

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If PA°=200 mm of Hg,PB°=100 mm of Hg and XAI=0.4 then, find XAIII ?

HARD
IMPORTANT

Two liquid A and B form an ideal solution. The ratio of vapour pressures of pure liquids A and B are 3:5. if the mole- fraction of A in the liquid solution at equilibrium with vapours, is 0.4, then the mole fraction of B in the vapour is

EASY
IMPORTANT

The following graph represents variation of boiling point with composition of liquid and vapours of binary liquid mixture. The graph is plotted at constant pressure, for a solution of mole fraction 0.5

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Which of the following statement(s) is correct.

HARD
IMPORTANT

The vapour pressure of water is 12.3kPa at 300 k. Now, calculate the vapour pressure of 1 molar solution of a solute in it.

MEDIUM
IMPORTANT

How we can prove that Raoult’s law as a special case of Henry’s law?

EASY
IMPORTANT

Raoult's law becomes a special case of Henry's law when KH=p0. In this equation, KH is 

EASY
IMPORTANT

Raoult's law becomes a special case of Henry's law when KH becomes equal to _____.

A. p0   B. p   C. p2

"Enter the correct answer as A, B or C."

MEDIUM
IMPORTANT

Condition at which Raoult's law becomes a special case of Henry's law?

EASY
IMPORTANT

Raoult's law becomes a special case of Henry's law when KH becomes equal to p1.

MEDIUM
IMPORTANT

At 300 K, the vapour pressure of a solution containing one mole of n-hexane and three moles of n-heptane is 550 mm of Hg. At the same temperature, if one more mole of n-heptane is added to this solution, the vapour pressure of the solution increases by 10 mm of Hg. What is the vapour pressure in mm Hg of n-heptane in its pure state?

EASY
IMPORTANT

A mixture of toluene and benzene forms a nearly ideal solution. Assume PB° and PT° to be the vapor pressures of pure benzene and toluene, respectively. The slope of the line obtained by plotting the total vapor pressure to the mole fraction of benzene is:

MEDIUM
IMPORTANT

In the pressure vs. the mole fraction of benzene curves/lines shown below, the total vapour pressure of an ideal mixture of benzene and toluene will follow the curve/line.

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MEDIUM
IMPORTANT

Vapour pressure of benzene is 200 mm Hg. When 2g of non-volatile solute is dissolved in 78g benzene, benzene solution has vapour pressure 195 mm Hg. Calculate the molar mass of the solute in gmol-1( molar mass of benzene = 78gmol-1).

EASY
IMPORTANT

Raoult's law states that for a solution of volatile liquids, the partial vapour pressure of each component of the solution is directly proportional to its mole fraction present in solution.

MEDIUM
IMPORTANT

Vapour pressure of A and B mixture at 80°C is given by P(in mm Hg)=100+200 xA, where xA is mole fraction of A. Solution is prepared by mixing 2 mol of A and 3 mol of B and if the vapours are removed and condensed into liquid and again brought to the temperature of 80°C, If the ratio of mole fraction of A in vapour state and mole fraction of B in vapour state above the condensate is x: 1, find value of 'x' is -

EASY
IMPORTANT

At 40°C, the vapour pressure (in torr) of methyl alcohol (A) and ethyl alcohol solution is represented by: P=120XA+138; where XA is mole fraction of
methyl alcohol. The value of PB° at limXA0 and PA° at limXB0 are :

EASY
IMPORTANT

The mass of a non-volatile solute of molar mass 40 g mol-1 that should be dissolved in 114 g of octane to lower its vapour pressure by 20% is :

MEDIUM
IMPORTANT

The vapour pressure of benzene at 80°C is lowered by 10 mm by dissolving 2 g of a non-volatile substance in 78 g of benzene. The vapour pressure of pure benzene at 80°C is 750 mm. The molecular mass of the substance will be :

EASY
IMPORTANT

Which condition is not satisfied by an ideal solution?

MEDIUM
IMPORTANT

At 40°C, vapour pressure in torr of methanol and ethanol solution is P=119X+135: where X is the mole fraction of methanol. Hence