NUMERICAL RELATED TO VAN'T HOFF FACTOR

Q.1 Calculate the osmotic pressure of 20% (wt./vol.) anhydrous Ca(N03)2 solution at 0°C assuming 100% ionisation. 

Q.2 The vapour pressure of a solution containing 2 g of NaCl in 100 g water, which dissociated in one Na and one CI" ion in water, is 751 mm, at 100°C. Calculate the degree of ionisation ofNaCl.

Q.3 17.4% (wt./vol.) K2S04 solution at 27°C is isotonic to 5.85% (wt./ vol.) NaCl solution at 27°C. If NaCl is 100% ionised, what is % ionisation of K2S04 in aq. solution? 

Q.4 A certain mass of a substance when dissolved in 100 g CfiHg lowers the freezing point by 1.28°C. The same mass of solute dissolved in 100 g of water lowers the freezing point by 1.40°C. If the substance has normal molecular weight in benzene and is completely dissociated in water, into how many ions does it dissociate in water? Kf for H2O and QH^, are 1.86 and 5.12 K mol-1 kg respectively.

Q.5 The vapour pressure of a solution containing 2 g of an electrolyte BA in 100 g water, which dissociates in one B+ and one A~ ion in water, is 751 mm, at 100°C. Calculate degree of ionisation of BA if its mol. wt. is 56.

Q.6 What will be the osmotic pressure of 0.1 M monobasic acid if its pH is 2 at 25°C

Q.7 A complex is represented as CoCl3 • XNH3. Its 0.1 molal solution in aqueous solution shows A7f = 0.558°. K( for H20 is 1.86 K molality"'. Assuming 100% ionisation of complex and co-ordination number of Co as six, calculate formula of complex. 

Answers:

1) 82 atm      2) 94.74%      3) 50%

4) 3        5) 86.41%      6) 2.69 atm