Assignment – 2     Chapter - Solution

Q11. Acetic acid associates in benzene to form a dimer. 1.65 gm of acetic acid when dissolved in 100 gm of benzene raised the B.P. by 0.36 °C. Calculate the Van’t Hoff factor and degree of association of acetic acid.   (Kb for benzene = 2.57 0C/m).

Q12. Find van’t Hoff factor of : a). CH3COOH in H2O,       b).  CH3COOH in benzene

Q13. A 0.1 M solution of potassium sulphate, K2SO4 is dissolved to the extent of 90%. What would be its osmotic pressure at 27 0C?

Q14. Why is vapour pressure of solution of glucose in water lower than that of water ?

Q15. What is the molarity of acetic acid containing 6 g of acetic acid per litre of solution?

Q16. What is expected van't Hoff factor for K4 [Fe(CN)6]?

Q17. What is anti-freeze?

Q18. Calculate the volume of 80% (by mass) of H2SO4 (density = 1.80 g/ml) required to prepare 1 litre of 0.2 molar H2SO4, (Relative atomic masses : H = 1, O = 16, S = 32).

Q19. Give one example each of miscible liquid pairs showing positive and negative deviations from Raoult's law. Give one reason each for such deviations.

Q20. Suggest the most important type of intermolecular attractive interaction in the following pairs.
               (i) n-hexane and n-octane.
               (ii) I2 and CCl4,  (iii) NaClO4 and water.
               (iv) methanol and acetone.

Q21. a. What is Raoult's law and what are its applications
b. Urea forms an ideal solution in water. Determine the vapour pressure of an aqueous solution containing 10% by mass of urea of 40oC. (Vapour pressure of water at 40oC = 55.3 mm of Hg). 

Q22. a).  Draw graph showing depression of freezing point due to non volatile solute.
b.   Calculate the freezing point of a solution containing 0.520 g of glucose (C6H12O6) dissolved in 80.20 g of water. [For water Kf = 1.86 K kg mol-1.]