Advertisements
Advertisements
प्रश्न
Calculate the mass of a non-volatile solute (molar mass 40 g mol−1) which should be dissolved in 114 g octane to reduce its vapour pressure to 80%.
Advertisements
उत्तर
Given: Vapour pressure of pure solvent octane `(p_1^0)` = p
Vapour pressure of the solution (p1) = 80% of p = 0.80 p
Molar mass of solute (M2) = 40 g mol−1
Mass of solvent octane (w1) = 114 g
Molar mass of solvent octane (M1) = 114 g mol−1
According to Raoult’s Law for a non-volatile solute:
`(p_1^0 - p)/p_1^0 = n_2/(n_1 + n_2)`
Number of moles of solvent octane (n1) = `114/114`
= 1 mol
Number of moles of solute (n2) = `w_2/40`
Substitute the values into Raoult’s Law formula:
`(p - 0.80 p)/p = (w_2/40)/(1 + w_2/40)`
`(0.20 p)/p = (w_2/40)/((40 + w_2)/40)`
0.2 = `w_2/(40 + w_2)`
0.2 × (40 + w2) = w2
8 + 0.2 w2 = w2
8 = w2 − 0.2 w2
8 = 0.8 w2
w2 = `8/0.8`
= 10 g
संबंधित प्रश्न
In non-ideal solution, what type of deviation shows the formation of maximum boiling azeotropes?
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?
Why does a solution containing non-volatile solute have higher boiling point than the pure solvent ?
What type of deviation is shown by a mixture of ethanol and acetone? Give reason.
The vapour pressures of pure liquids A and B are 450 and 700 mm Hg respectively, at 350 K. Find out the composition of the liquid mixture if the total vapour pressure is 600 mm Hg. Also, find the composition of the vapour phase.
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?
100 g of liquid A (molar mass 140 g mol−1) was dissolved in 1000 g of liquid B (molar mass 180 g mol−1). The vapour pressure of pure liquid B was found to be 500 torr. Calculate the vapour pressure of pure liquid A and its vapour pressure in the solution if the total vapour pressure of the solution is 475 Torr.
What type of azeotrope is formed by positive deviation from Raoult’s law?
Some liquids on mixing form 'azeotropes'. What are 'azeotropes'?
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.
Define Raoult’s law for the elevation of the boiling point of a solution.
An aqueous solution of hydrochloric acid:
On the basis of information given below mark the correct option.
(A) In bromoethane and chloroethane mixture intermolecular interactions of A–A and B–B type are nearly same as A–B type interactions.
(B) In ethanol and acetone mixture A–A or B–B type intermolecular interactions are stronger than A–B type interactions.
(C) In chloroform and acetone mixture A–A or B–B type intermolecular interactions are weaker than A–B type interactions.
On the basis of information given below mark the correct option.
On adding acetone to methanol some of the hydrogen bonds between methanol molecules break.
The vapour pressure of pure liquid X and pure liquid Y at 25°C are 120 mm Hg and 160 mm Hg respectively. If equal moles of X and Y are mixed to form an ideal solution, calculate the vapour pressure of the solution.
An azeotropic mixture of two liquids will have a boiling point lower than either of the two liquids when it ______.
