Assignment - 1


Chapter - Solution


Q1. The Henry’s law constant for the solubility of N2 gas in water at 298 K is 1.0 x 105 atm. The mole fraction of N2 in air is 0.8. Find the number of moles of N2 from air dissolved in 10 moles of water at 298 K and 5 atm pressure.

Q2. At a certain temperature, the vapour pressure of pure ether is 646 mm and that of pure acetone is 283 mm. Calculate the mole fraction of each component in the vapour state if the mole fraction of ether in the solution is 0.50.

Q3. 4.375 g of a substance when dissolved in 36.0 g of water, lowered its vapour pressure by 0.5 mm at a given temperature. The vapour pressure of water at this temperature is 25.0 mm. Calculate the molecular weight of solute. 

Q4. Assuming ideal behaviour, calculate the vapour pressure of 1.0 molal solution of a non- volatile molecular solute in water at 500C is 0.122 atm.

Q5. The vapour pressure of pure water 250C is 23.76 torr. What is the paour pressure of 100 gm of water to which 100 gm of C6H12O6 (glucose) has been added ? 

Q6. The boiling point of a solution made by dissolving 12.0 gm of glucose in 100 gm of water is 100.340C. Calculate the molecular weight of glucose. Kb for water = 0.520C/m.

Q7. Blood freezes at 272.44 K and a solution of 3.0 gm of Urea in 250 gm of water freezes at 272.63 K. Calculate osmotic pressure of blood at 310 K. (Assume density of blood at 310 K to be 1 g/cc).

Q8. Calculate the freezing point depression and boiling point elevation of a solution of  10.0 gm of urea (MB  = 60) in 50.0 gm of water at 1 atm. pressure. Kb  and Kf   for water are 0.520C/m and 1.860C/m respectively.

Q9. The boiling point elevation constant for benzene is 2.570C/m. The boiling point of benzene is 80.10C. Determine the boiling point of a solution formed when 5.0 gm of C14H12 is dissolved in 15 gm of benzene.

Q10. What mass of sugar, C12H22O11 (M0 = 342) must be dissolved in 4.0 kg of H2O to yield solution that will freeze at –3.72°C. (Take Kf  = 1.86°C/m).