# Dalton's Law of Partial Pressures

## Trending Questions

**Q.**At 20oC, the vapour pressure of benzene is 70 torr and that of methyl benzene is 20 torr. The mole fraction of benzene in the vapor phase at 20oC above an equimolar mixture of benzene and methyl benzene is x×10−2. The value of x (Nearest integer)

**Q.**An ideal binary liquid solution of A and B has a vapour pressure of 900 mm of Hg. It is distilled at constant temparature till 23 of the original amount is distilled. If the mole fraction of ′A′ in residue and mole fraction of B in condensate are 0.3 and 0.7 respectively and vapour pressure of residue is 860 mm of Hg then idenetify the correct options.

- The initial mixture taken should be an equimolar mixture of A and B
- The first vapours formed will have more moles of A as compared to moles of B
- PA=1000 mm of Hg
- The vapour pressure above the condenstate will be 920 mm of Hg at same temparature

**Q.**

What is the difference between vapor pressure and partial pressure?

**Q.**

Equal masses of methane and oxygen are mixed in an empty container at 25 degrees centigrade. The fraction of the total pressure exerted by Oxygen is:

Options1)1/3

2)1/2

3)2/3

4)1/3*273/298

Answer is option1

**Q.**Which of the following mixture of gases does not obey Dalton's law of partial pressures?

- O2 and CO2
- N2 and O2
- Cl2 and O2
- NH3 and HCl

**Q.**2O3(g)⇌3O2(g)

At 300K, ozone is fifty percent dissociated. The standard free energy change at this temperature and 1 atm pressure is (-)

[Given: \ln1.35=0.3 and R=8.3JK−1mol−1]

**Q.**A sealed flask with a capacity of 2 dm3 contains 11 g of propane gas. The flask is so weak that it will burst if the pressure becomes 2 MPa. The minimum

temperature at which the flask will burst is _____∘C. [Nearest integer]

(Given: R=8.3 J K–1 mol–1, Atomic masses of C and H are 12u and 1u, respectively.) (Assume that

propane behaves as an ideal gas.)

**Q.**Raoult law explanation for non volatile solute.

**Q.**

the vapour pressure of two liquids A and B in their pure states are in ratio 1:2. A binary solution of A and B has A and B in mole proportion 1:2. The mole fraction of A in vapour phase of the solution will be ??

is the answer 0.33 or 0.2( because as the molefraction of A in vapour phase is used should we not use daltons law of partial pressure??)

**Q.**

A gaseous mixture of an equal mass of ${\mathrm{CH}}_{4}$ and ${\mathrm{O}}_{2}$ is stored over water. if the total pressure is $0.5\mathrm{atm}$ then the partial pressure of dry ${\mathrm{CH}}_{4}$ gas is ?(aqueous tension $=0.2\mathrm{atm}$)

**Q.**A neon-dioxygen mixture contains 70.6 g dioxygen and 167.5 g neon. If the pressure of the mixture of gases in the cylinder is 25 bar, what is the partial pressure of dioxygen and neon in the mixture?

- PO2=19.75 bar, PNe=5.25 bar
- PO2=12.75 bar, PNe=12.25 bar
- PNe=19.75 bar, PO2=5.25 bar
- PNe=12.75 bar, PO2=12.25 bar

**Q.**

The pressure of a 1:4 mixture of dihydrogen and dioxygen enclosed in a vessel is one atmosphere. What would be the partial pressure of dioxygen?

(a) 0.8×105 atm (b) 0.008 Nm−2 (c) 8×104 Nm−2 (d) 0.25 atm

**Q.**

A mixture of dihydrogen and dioxygen at one bar pressure contains 20% by weight of dihydrogen. Calculate the partial pressure of dihydrogen.

**Q.**

Two solids dissociated as follows

$\mathrm{A}\left(\mathrm{s}\right)\rightleftharpoons \mathrm{B}\left(\mathrm{g}\right)+\mathrm{C}\left(\mathrm{g}\right){\mathrm{K}}_{\mathrm{P}1}=\mathrm{x}{\mathrm{atm}}^{2}$

$\mathrm{D}\left(\mathrm{s}\right)\rightleftharpoons \mathrm{C}\left(\mathrm{g}\right)+\mathrm{E}\left(\mathrm{g}\right){\mathrm{K}}_{\mathrm{P}2}=\mathrm{y}{\mathrm{atm}}^{2}$

The total pressure when both the solids dissociate simultaneously is:

**Q.**A vessel is filled with a mixture of oxygen and nitrogen. At what ratio of partial pressure will the mass of the gases be identical?

- p(O2)=0.785 p(N2)
- p(O2)=8.75 p(N2)
- p(O2)=11.4 p(N2)
- p(O2)=0.875 p(N2)

**Q.**In Duma’s method of estimation of N 0.35 g of an organic compound gave 55mL of nitrogen collected at 300K temperature and 715mm pressure. The % of N in the compound would be (aqueous tension at 300K=15mm)

- 15.45
- 14.45
- 17.45
- 16.45

**Q.**

A and B are ideal gases. The molecular weights of A and B are in the ratio of 1 : 4 . The pressure of a gas mixture containing equal weights of A and B is P atm. What is the partial pressure (in atm) of B in the mixture?

P/5

P/2

P/2.5

3P/4

**Q.**The partial pressure of ethane over a saturated solution containing 6.56×10−2g of ethane is 1 bar. If the solution contains 5×10−2g of ethane, then what will be the partial pressure of the gas?

**Q.**At a given temprature , density of gas x is twice as that of gas y and molar mass of x is one third of gas y.The ratio of their pressures will be?

**Q.**under identical conditions of pressure and temperature2L of gaseous mixture (H2 and CH4) effuses through a hole in 5 min whereas 2 litres of a gasX of molecular mass 36 takes 10 minutes to effuses through the same hole. The mole ratio of H2: CH4 in the mixture i

**Q.**Which of the following is correct for an ideal solution?

- Raoult's law is obeyed for entire concentration range and temperatures
- ΔHmix=0
- ΔVmix=0
- ΔSmix=0

**Q.**The partial pressure of ethane over a solution containing 6.56 x 10 g ofethane is 1 bar. If the solutioncontains 5.00 x 10-2 g of ethane, then whatshall be the partial pressure of the gas?

**Q.**A 1:1 mixture (by weight) of hydrogen and helium is enclosed in a one-litre flask at 0 ∘C. Assuming ideal behaviour, the partial pressure of helium is found to be 0.42 atm, then the concentration of hydrogen would be:

- 0.0375 M
- 0.028 M
- 0.0562 M
- 0.0187 M

**Q.**Assertion: Effusion rate of oxygen is smaller than nitrogen. Reason: Molecular size of nitrogen is smaller than oxygen

- Both assertion and reason are true and reason is the correct explanation of assertion
- Both assertion and reason are true but reason is not the correct explanation of assertion
- Assertion is true but reason is false
- Both assertion and reason are false

**Q.**The vapour pressures of ethanol and methanol are 42.0 mm and 88.5 mm Hg, respectively. An ideal solution is formed at the same temperature by mixing 46.0 g of ethanol with 16.0 g of methanol. The mole fraction of ethanol in the vapour is:

- 0.487
- 0.352
- 0.892
- 0.665

**Q.**

The gas having the highest partial pressure in the atmosphere is –

**Q.**Consider the following equilibrium in a closed container:

PCl5(g)⇌PCl3(g)+Cl2(g)

PCl5 gas at a certain pressure is introduced in the container at 27 oC. However, the total pressure at equilibrium at 207 oC was found to be double the initial value. The % dissociation of PCl5 at 207 oC is:

**Q.**the vapour pressure of pure liquids Aand B are 200 and 350 mm hg respectively , at 300k . mole fraction of liquid A in a mixture having its vapour pressure 305mm of Hg i

**Q.**

A gaseous mixture of three gases A, B and C has a pressure of 10atm. The total number of moles of all gases is 10. The partial pressure of A and B are 3 and 1 atm respectively. If C has a molecular weight of 2, then find the weight of C in grams present in the mixture.

6

3

12

8

**Q.**

Dalton’s law of partial pressure is not applicable to a mixture of