Henry's Law and Raoult's Law

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JEE Advanced 2026

Comprehension Passage

Two volatile liquids A and B form an ideal solution. Consider a 5 molal solution of B in A inside a closed container having a total vapour pressure of

100 mm Hg

300 K

. The vapour pressure of pure A at

300 K

105 mm Hg

. Assume that A and B behave as ideal gases in the vapour phase. Given: The gas constant

R = 0.08 L atm K^{- 1} mol^{- 1}

Molar mass of A is

50 g mol^{- 1}

Molar mass of B is

57 g mol^{- 1}

Density of liquid B at

300 K

0.5 g/mL

1 atm = 760 mm Hg

Question 1:

At $300 K$ , the ratio of the molar volume of pure B in vapour phase to its molar volume in liquid phase is _____.

Question 2:

The mole fraction of B in vapour phase which is in equilibrium with this solution is ____.

JEE Advanced 2016

LEVELJEE Main

Mixture(s) showing positive deviation from Raoult's law at $3 5^{\circ} C$ is (are)

* Multiple Correct Options

(A)

carbon tetrachloride + methanol

(B)

carbon disulphide + acetone

Liquids A and B form ideal solution over the entire range of composition. At temperature T, equimolar binary solution of liquids A and B has vapour pressure 45 Torr. At the same temperature, a new solution of A and B having mole fractions $x_{A}$ and $x_{B}$ , respectively, has vapour pressure of 22.5 Torr. The value of $x_{A} / x_{B}$ in the new solution is_______. (Given that the vapour pressure of pure liquid A is 20 Torr at temperature T)

JEE Advanced 2020

LEVELJEE Main

Liquids A and B form ideal solution for all compositions of A and B at 25°C. Two such solutions with 0.25 and 0.50 mole fractions of A have the total vapor pressures of 0.3 and 0.4 bar, respectively. What is the vapor pressure of pure liquid B in bar?

JEE Advanced 2017

LEVELJEE Advanced

For a solution formed by mixing liquids L and M, the vapour pressure of L plotted against the mole fraction of M in solution is shown in the following figure, Here $x_{L}$ and $x_{M}$ represent mole fractions of L and M, respectively, in the solution. the correct statement(s) applicable to this system is(are) –

* Multiple Correct Options

(A)

Attractive intramolecular interactions between L–L in pure liquid L and M–M in pure liquid M are stronger than those between L–M when mixed in solution

(B)

The point Z represents vapour pressure of pure liquid M and Raoult's law is obeyed when

x_{L} \to 0

(C)

The point Z represents vapour pressure of pure liquid L and Raoult's law is obeyed when

x_{L} \to 1

(D)

The point Z represents vapour pressure of pure liquid M and Raoult's law is obeyed from

x_{L} = 0

x_{L} = 1

JEE Main 2020

LEVELJEE Main

At $3 5^{\circ} C$ , the vapour pressure of $CS_{2}$ is $512 mm Hg$ and that of acetone is $344 mm Hg$ . A solution of $CS_{2}$ in acetone has a total vapour pressure of $600 mm Hg$ . The false statement amongst the following is

(A)

Raoult's law is not obeyed by this system

(B)

CS_{2}

and acetone are less attracted to each other than to themselves

(C)

a mixture of

100 mL CS_{2}

and

100 mL

acetone has a volume

< 200 mL

(D)

heat must be absorbed in order to produce the solution at

3 5^{\circ} C

LEVELJEE Main

On mixing, heptane and octane form an ideal solution. At $373 K$ , the vapour pressures of the two liquid components (heptane and octane) are $105 kPa$ and $45 kPa$ , respectively. Vapour pressure of the solution obtained by mixing $25 g$ of heptane and $35 g$ of octane will be (molar mass of heptane $= 100 g mol^{- 1}$ and of octane $= 114 g mol^{- 1}$ ).

(A)

72.0 kPa

(B)

36.1 kPa

(C)

96.2 kPa

(D)

144.5 kPa

JEE Main 2020

LEVELJEE Advanced

At 300 K, the vapour pressure of a solution containing 1 mole of n-hexane and 3 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 ........... ?

JEE Main 2021

LEVELJEE Main

The vapour pressures of $A$ and $B$ at $2 5^{\circ} C$ are $90 mm Hg$ and $15 mm Hg$ respectively. If $A$ and $B$ are mixed such that the mole-fraction of $A$ in the mixture is $0.6$ , then the mole fraction of $B$ in the vapour phase is $x \times 1 0^{- 1}$ . The value of $x$ is ......... .

JEE Main 2019

LEVELJEE Main

Liquid $M$ and liquid $N$ form an ideal solution. The vapour pressures of pure liquids $M$ and $N$ are $450$ and $700 mmHg$ , respectively, at the same temperature. Then correct statement is $x_{M} = mole fraction of M in solution;$ $x_{N} = mole fraction of N in solution;$ $y_{M} = mole fraction of M in vapour phase;$ $y_{N} = mole fraction of N in vapour phase$

(A)

\frac{x _{M}}{x _{N}} > \frac{y _{M}}{y _{N}}

(B)

\frac{x _{M}}{x _{N}} = \frac{y _{M}}{y _{N}}

(C)

\frac{x _{M}}{x _{N}} < \frac{y _{M}}{y _{N}}

(D)

(x_{M} - y_{M}) < (x_{N} - y_{N})

JEE Main 2020

LEVELJEE Main

A graph of vapour pressure and temperature for three different liquids X, Y, and Z is shown below : The following inference are made : A. X has higher intermolecular interactions compared to Y. B. X has lower intermolecular interactions compared to Y. C. Z has lower intermolecular interactions compared to Y. The correct inference(s) is/are :

A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of $290 mm$ at $300 K$ . The vapour pressure of propyl alcohol is $200 mm$ . If the mole fraction of ethyl alcohol is $0.6$ , its vapour pressure (in mm) at the same temperature will be

Two open beakers one containing a solvent and the other containing a mixture of that solvent with a non-volatile solute are together sealed in a container. Over time

(A)

the volume of the solution decreases and the volume of the solvent increases

(B)

the volume of the solution does not change and the volume of the solvent decreases

(C)

the volume of the solution increases and the volume of the solvent decreases

(D)

the volume of the solution and the solvent does not change

LEVELJEE Main

Which of the following liquid pairs shows a positive deviation from Raoult's law?

(A)

Water — hydrochloric acid

Two liquids $X$ and $Y$ form an ideal solution at $300 K$ , vapour pressure of the solution containing $1 mol$ of $X$ and $3 mol$ of $Y$ is $550 mmHg$ . At the same temperature, if $1 mol$ of $Y$ is further added to this solution, vapour pressure of the solution increases by $10 mm Hg$ . Vapour pressure (in $mmHg$ ) of $X$ and $Y$ in their pure states will be, respectively

(A)

200

and

300

(B)

300

and

400

(C)

400

and

600

(D)

500

and

600

JEE Main 2019

LEVELJEE Main

Liquids $A$ and $B$ form an ideal solution in the entire composition range. At $350 K$ , the vapour pressures of pure $A$ and pure $B$ are $7 \times 1 0^{3} Pa$ and $12 \times 1 0^{3} Pa$ , respectively. The composition of the vapour in equilibrium with a solution containing $40$ mole percent of $A$ at this temperature is

(A)

x_{A} = 0.76; x_{B} = 0.24

(B)

x_{A} = 0.28; x_{B} = 0.72

(C)

x_{A} = 0.4; x_{B} = 0.6

(D)

x_{A} = 0.37; x_{B} = 0.63

LEVELJEE Main

Benzene and toluene form nearly ideal solutions. At $2 0^{\circ} C$ , the vapour pressure of benzene is $75 torr$ and that of toluene is $22 torr$ . The partial vapour pressure of benzene at $2 0^{\circ} C$ for a solution containing $78 g$ of benzene and $46 g$ of toluene in torr is

An open beaker of water in equilibrium with water vapour is in a sealed container. When few grams of glucose are added to the beaker of water, the rate at which water molecules

(A)

leaves the solution decreases

(B)

leaves the solution increases

(C)

leaves the vapour increases

(D)

leaves the vapour decreases

JEE Main 2019

LEVELJEE Advanced

For the solution of the gases $w, x, y$ and $z$ in water at $298 K$ , the Henry's law constants ( $K_{H}$ ) are $0.5, 2, 35$ and $40 K bar$ , respectively. The correct plot for the given data is

At $2 0^{\circ} C$ , the vapour pressure of benzene is 70 torr and that of methyl benzene is 20 torr. The mole fraction of benzene in the vapour phase at $2 0^{\circ} C$ above an equimolar mixture of benzene and methyl benzene is...... $\times 1 0^{- 2}$ . (Nearest integer)

JEE Main 2021

LEVELJEE Main

The water having more dissolved $O_{2}$ is

8 0^{\circ} C

4^{\circ} C

LEVELBoard

In a mixture of $A$ and $B$ , components show negative deviation when

(A)

A - B

interaction is stronger than

A - A

and

B - B

interaction

(B)

A - B

interaction is weaker than

A - A

and

B - B

interaction

(C)

Δ V_{mix} > 0, Δ S_{mix} > 0

(D)

Δ V_{mix} = 0, Δ S_{mix} > 0

JEE Main 2009

LEVELJEE Main

A binary liquid solution is prepared by mixing n-heptane and ethanol. Which one of the following statements is correct regarding the behaviour of the solution?

(A)

The solution formed is an ideal solution

(B)

The solution is non-ideal, showing positive deviation from Raoult's law

(C)

The solution is non-ideal, showing negative deviation from Raoult's law

(D)

n-heptane shows positive deviation while ethanol show negative deviation from Raoult's law

JEE Main 2019

LEVELJEE Main

Which one of the following statements regarding Henry's law is not correct?

(A)

Different gases have different

K_{H}

(Henry's law constant) values at the same temperature

(B)

Higher the value of

K_{H}

at a given pressure, higher is the solubility of the gas in the liquids

(C)

The value of

K_{H}

increases with increase of temperature and

K_{H}

is function of the nature of the gas

(D)

The partial pressure of the gas in vapour phase is proportional to the mole fraction of the gas in the solution

JEE Main 2021

LEVELJEE Main

The oxygen dissolved in water exerts a partial pressure of $20 kPa$ in the vapour above water. The molar solubility of oxygen in water is ...... $\times 1 0^{- 5} mol dm^{- 3}$ . (Round off to the nearest integer). [Given, Henry's law constant ( $K_{H}$ ) $= 8.0 \times 1 0^{4} kPa$ for $O_{2}$ , density of water with dissolved oxygen $= 1.0 kg dm^{- 3}$ ].

Comprehension Passage

.math-text-wrapper .katex { font-size: 1.05em !important; } .math-text-wrapper .katex-display { margin: 1rem 0 !important; } At 300 K, the ratio of the molar volume of pure B in vapour phase to its molar volume in liquid phase is _____.

The mole fraction of B in vapour phase which is in equilibrium with this solution is ____.

.math-text-wrapper .katex { font-size: 1.05em !important; } .math-text-wrapper .katex-display { margin: 1rem 0 !important; } Mixture(s) showing positive deviation from Raoult's law at 35∘C is (are)

Liquids A and B form ideal solution for all compositions of A and B at 25°C. Two such solutions with 0.25 and 0.50 mole fractions of A have the total vapor pressures of 0.3 and 0.4 bar, respectively. What is the vapor pressure of pure liquid B in bar?

Two open beakers one containing a solvent and the other containing a mixture of that solvent with a non-volatile solute are together sealed in a container. Over time

Which of the following liquid pairs shows a positive deviation from Raoult's law?

An open beaker of water in equilibrium with water vapour is in a sealed container. When few grams of glucose are added to the beaker of water, the rate at which water molecules

.math-text-wrapper .katex { font-size: 1.05em !important; } .math-text-wrapper .katex-display { margin: 1rem 0 !important; } For the solution of the gases w,x,y and z in water at 298 K, the Henry's law constants (KH​) are 0.5,2,35 and 40 K bar, respectively. The correct plot for the given data is

.math-text-wrapper .katex { font-size: 1.05em !important; } .math-text-wrapper .katex-display { margin: 1rem 0 !important; } The water having more dissolved O2​ is

.math-text-wrapper .katex { font-size: 1.05em !important; } .math-text-wrapper .katex-display { margin: 1rem 0 !important; } In a mixture of A and B, components show negative deviation when

A binary liquid solution is prepared by mixing n-heptane and ethanol. Which one of the following statements is correct regarding the behaviour of the solution?

Which one of the following statements regarding Henry's law is not correct?

At $300 K$ , the ratio of the molar volume of pure B in vapour phase to its molar volume in liquid phase is _____.

Mixture(s) showing positive deviation from Raoult's law at $3 5^{\circ} C$ is (are)

For the solution of the gases $w, x, y$ and $z$ in water at $298 K$ , the Henry's law constants ( $K_{H}$ ) are $0.5, 2, 35$ and $40 K bar$ , respectively. The correct plot for the given data is

The water having more dissolved $O_{2}$ is

In a mixture of $A$ and $B$ , components show negative deviation when