Single Choice

The relative lowering of the vapour pressure is equal to the ratio between the number:

Asolute molecules to the solvent molecules
Bsolute molecules to the total molecules in the solution
Correct Answer
Csolvent molecules to the total molecules in the solution
Dsolvent molecules to the total number of ions of the solute

Solution

Relative Lowering of the vapour pressure of the solvent:
When a non-volatile solute is added to a solvent, the vapour pressure of the solution decreases.
According to Raoult's Law, the vapour pressure of a solvent (P1) in a solution containing a non-volatile solute is given by
P1=x1P
°
1
Vapour pressure of the pure solvent = P
°
1
Vapour pressure of the solvent in solution = P1
ΔP1=P1°−P1
=P1°−x1P1°
=P1°(1−x1)
In a binary solution, 1−x1=x2
ΔP1=P1°x2
ΔP1/P1°=(P1°−P1)/P1°=x2
The lowering of vapour pressure relative to the vapour pressure of the pure solvent is called a relative lowering of vapour pressure.
ΔP1/P1° → Relative lowering of Vapour pressure
Thus, the relative lowering in vapour pressure depends only on the concentration of solute particles and is independent of their identity.

SIMILAR QUESTIONS

Solutions

If Raoult's law is obeyed, then vapour pressure of the solvent in a solution is directly proportional to:

Solutions

The weight of an empty china dish is 39 g and when a saturated solution of potassium nitrate is poured into, its weight is 108 g at $$50^{\circ}C$$. After evaporating the solution to dryness, if the weight of the dish along with the crystals is 72 g then the solubility of potassium nitrate at $$50^{\circ} C$$ is .....................

Solutions

For a dilute solution, Raoult's law states that:

Solutions

Which one of the following is incorrect for ideal solution?

Solutions

The mixture which shows positive deviation from Raoult’s law is

Solutions

For a dilute solution, Raoult's law states that:

Solutions

Which of the following is satisfied by an ideal solution?

Solutions

What are the similarities between Raoult's Law and Henry's Law

Solutions

State the following : Raoult's law in its general form in reference to solutions .

Solutions

State Raoult's law for the solution containing volatile components. Write two differences between an ideal solution and a non-ideal solution.

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