Advertisements
Advertisements
प्रश्न
Vapour pressure of pure water at 298 K is 23.8 mm Hg. 50 g of urea (NH2CONH2) is dissolved in 850 g of water. Calculate the vapour pressure of water for this solution and its relative lowering.
Advertisements
उत्तर
Given, P0 = 23.8 mm Hg
w1 = 850 g, M1 (water) = 18 g mol−1
w2 = 50 g, M2 (urea) = 60 g mol−1
Ps = ?, `("P"^0 - "P"_"s")/"P"^0` = ?
∴ n1 = `850/18` = 47.22
∴ n2 = `50/60` = 0.83
Applying Raoult's law, `("P"^0 - "P"_"s")/"P"^0 = "n"_2/("n"_1+"n"_2)`
or, `("P"^0 - "P"_"s")/"P"^0 = 0.83/(47.22 + 0.83)`
`("P"^0 - "P"_"s")/"P"^0 = 0.83/48.05`
`("P"^0 - "P"_"s")/"P"^0` = 0.017
Thus, the relative lowering of vapour pressure = 0.017
Again, `(Δ"P")/"P"^0` = 0.017
∴ ΔP = 0.017 × 23.8
or, P0 − Ps = 0.017 × 23.8
or, Ps = 23.8 − (0.017 × 23.8)
or, Ps = 23.4 mm Hg
Thus, the vapour pressure of water in the solution is 23.4 mm Hg.
APPEARS IN
संबंधित प्रश्न
State Raoult’s law for the solution containing volatile components
What is meant by positive deviations from Raoult's law? Give an example. What is the sign of ∆mixH for positive deviation?
Define azeotropes.
An aqueous solution of 2% non-volatile solute exerts a pressure of 1.004 bar at the normal boiling point of the solvent. What is the molar mass of the solute?
Benzene and toluene form ideal solution over the entire range of composition. The vapour pressure of pure benzene and toluene at 300 K are 50.71 mm Hg and 32.06 mm Hg respectively. Calculate the mole fraction of benzene in vapour phase if 80 g of benzene is mixed with 100 g of toluene.
What type of azeotrope is formed by positive deviation from Raoult’s law?
What is meant by negative deviation from Raoult's law? Give an example. What is the sign of ∆mixH for negative deviation?
For the reaction :
\[\ce{2NO_{(g)} ⇌ N2_{(g)} + O2_{(g)}}\];
ΔH = -heat
Kc = 2.5 × 102 at 298K
What will happen to the concentration of N2 if :
(1) Temperature is decreased to 273 K.
(2) The pressure is reduced
Match the following:
| (i) | Colligative property | (a) | Polysaccharide |
| (ii) | Nicol prism | (b) | Osmotic pressure |
| (iii) | Activation energy | (c) | Aldol condensation |
| (iv) | Starch | (d) | Polarimeter |
| (v) | Acetaldehyde | (e) | Arrhenius equation |
A solution containing 8.44 g of sucrose in 100 g of water has a vapour pressure 4.56 mm of Hg at 273 K. If the vapour pressure of pure water is 4.58 mm of Hg at the same temperature, calculate the molecular weight of sucrose.
What will be the vapour pressure of a solution containing 5 moles of sucrose (C12H22O11) in 1 kg of water, if the vapour pressure of pure water is 4.57 mm of Hg? [C = 12, H = 1, O = 16]
Raoult’s law states that for a solution of volatile liquids the partial pressure of each component in the solution is ____________.
Minimum boiling azeotrope is formed by the solution which showed
An aqueous solution of hydrochloric acid:
Considering the formation, breaking and strength of hydrogen bond, predict which of the following mixtures will show a positive deviation from Raoult’s law?
Using Raoult’s law explain how the total vapour pressure over the solution is related to mole fraction of components in the following solutions.
\[\ce{NaCl(s) and H2O(l)}\]
Two liquids X and Y form an ideal solution. The mixture has a vapour pressure of 400 mm at 300 K when mixed in the molar ratio of 1 : 1 and a vapour pressure of 350 mm when mixed in the molar ratio of 1 : 2 at the same temperature. The vapour pressures of the two pure liquids X and Y respectively are ______.
A solution of a non-volatile solute in water freezes at −0.30°C. The vapour pressure of pure water at 298 K is 23.51 mm Hg and Kf for water is 1.86 degree/mol. The vapour pressure of rain solution at 298 K is ______ mm Hg.
