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Lowering of vapour pressure by a non-volatile solute (Raoult's law)

This type of question, asked 7 times: 27 Jul 2022, 6 Apr 2023, 11 Apr 2023, 12 Apr 2023, 15 Apr 2023, 23 Jan 2025, 6 Apr 2026 S1. All 7 questions below, oldest first.

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  1. Question 1

    27 Jul 2022

    144
    When a certain amount of solid A is dissolved in 100 g100\text{ }g of water at 25∘C25^{\circ}C to make a dilute solution, the vapour pressure of the solution is reduced to one-half of that of pure water. The vapour pressure of pure water is 23.76mmHg23.76mmHg. The number of moles of solute AA added is (Nearest Integer)

  2. Question 2

    6 Apr 2023

    54
    Mass of Urea (NH2CONH2)\left( NH_{2}CONH_{2} \right) required to be dissolved in 1000 g1000\text{ }g of water to reduce the vapour pressure of water by 25%25\% is......g. (Nearest integer) Given: Molar mass of N, C, O and H are 14, 12, 16 and 1 g mol−11\text{ }g{\text{ }mol}^{- 1} respectively.

  3. Question 3

    11 Apr 2023

    137
    What weight of glucose must be dissolved in 100 g100\text{ }g of water to lower the vapour pressure by 0.20 mm0.20\text{ }mm HgHg ? (Assume dilute solution is being formed) Given: Vapour pressure of pure water is 54.2 mm54.2\text{ }mm HgHg at room temperature. Molar mass of glucose is 180 g mol−1180\text{ }g{\text{ }mol}^{- 1}.

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  4. Question 4

    12 Apr 2023

    56
    80 mole percent of MgCl2MgCl_{2} is dissociated in aqueous solution. The vapour pressure of 1.0 molal aqueous solution of MgCl2MgCl_{2} at 38∘C38^{\circ}C is ____mm Hg. (Nearest integer) Given: Vapour pressure of water at 38∘C38^{\circ}C is 50 mmHgmmHg

  5. Question 5

    15 Apr 2023

    56
    The vapour pressure of 30%(w/v)30\%(w/v) aqueous solution of glucose is _____mmHg\_\_\_\_\_mmHg at 25∘C25^{\circ}C. [Given: The density of 30%(w/v)30\%(w/v), aqueous solution of glucose is 1.2 g cm−31.2\text{ }g{\text{ }cm}^{- 3} and vapour pressure of pure water is 24 mmHg24\text{ }mmHg.] (Molar mass of glucose is 180 g mol−1180\text{ }g{\text{ }mol}^{- 1}.)

  6. Question 6

    23 Jan 2025

    108
    When a non-volatile solute is added to the solvent, the vapour pressure of the solvent decreases by 10 mm of Hg . The mole fraction of the solute in the solution is 0.2 . What would be the mole fraction of the solvent if decrease in vapour pressure is 20 mm of Hg ?

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  7. Question 7

    6 Apr 2026 S1

    31
    When 0.25 moles of a non-volatile, non-ionizable solute was dissolved in 1 mole of a solvent the vapor pressure of solution was x%x\% of vapor pressure of pure solvent. What is the value of x%x\%?

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