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प्रश्न
Give two points to explain why vapour pressure of solvent is lowered by dissolving nonvolatile solute into it.
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उत्तर
- Vapour pressure of a liquid depends on the ease with which the molecules escape from the surface of liquid. When nonvolatile solute is dissolved in a solvent, some of the surface molecules of solvent are replaced by nonvolatile solute molecules. These solute molecules do not contribute to vapour above the solution.
- Thus, the number of solvent molecules available for vaporization per unit surface area of a solution is less than the number at the surface of pure solvent. As a result the solvent molecules at the surface of solution vaporize at a slower rate than pure solvent. This results in lowering of vapour pressure.
संबंधित प्रश्न
Answer the following.
How vapour pressure lowering is related to a rise in the boiling point of solution?
According to Raoult’s law, relative lowering of vapour pressure of solution containing dissolved nonvolatile solute _______.
Write the expression for relative lowering of vapour pressure.
Which of the following is NOT a colligative property?
The vapour pressure of solvent decreases by 1 O mm Hg, if mole fraction of non-volatile solute is 0.2. Calculate vapour pressure of solvent.
The vapour pressure of pure solvent and solution are 120 mm Hg and 108 mm Hg respectively. The mole fraction of the solvent in the solution is ____________.
Relative lowering of vapour pressure of a solution of non-volatile solute depend only on ____________.
Which of the following is CORRECT for a solution containing non-volatile solute in it?
The vapour pressure of pure benzene (molar mass 78 g/mol) at a certain temperature is 640 mm Hg. A nonvolatile solute of mass 2.315 g is added to 40 g of benzene. The vapour pressure of the solution is 600 mm Hg. The molar mass of solute is ______.
According to Raoult's law, relative lowering of vapour pressure for a solution containing a nonvolatile solute is equal to ____________.
Which of the following is INCORRECT expression in terms of vapour pressure of pure solvent `("P"_1^0)` and that of solution (P)?
The vapour pressure of water at 20°C is 17 mm Hg. The vapour pressure of solution containing 2.8 g urea in 50 g of water is ____________.
Which of the following changes will cause increase in vapour pressure of 1 molal aqueous KI solution at same temperature?
What will be the molar mass of solute if vapour pressure of pure benzene is 450 mm Hg when 1.5 g of non-volatile solute is added to 30 g of benzene?
(Vapour pressure of solution= 400 mm Hg, Atomic mass C = 12, H = 1)
Identify the correct statement from the following:
38.4 g of unknown substance (molar mass 384 g mol-1) and 116 g of acetone is used to prepare a solution at 313 K. If vapour pressure of pure acetone (molar mass 58 g mol-1) is 0.842 atmosphere, what is the vapour pressure of solution?
12 g of a nonvolatile solute dissolved in 108 g of water produces the relative lowering of vapour pressure of 0.1. The molecular mass of the solute is ______.
The vapour pressure of a solvent A is 0.80 atm. When a non-volatile substance B is added to this solvent its vapour pressure drops to 0.6 atm. the mole fraction of B in the solution is ______.
Which of the following solutions will have the maximum lowering of vapour pressure at 300 K?
The vapour pressure of 100 g of water reduces from 17.53 mm to 17.22 mm when 17.10 g, of substance X is dissolved in it. Substance X can be ______.
State and explain Raoult's law for the solution of non-volatile solutes.
