(ii) Could this substance be kept in car radiator during summer( very 10.(a) () Briefly explain the effect of presence of impurities on a pure solvent in respect of its
freezing point.
(ii) In an experiment 1.35g of solute were dissolved in 72.3cm' of water and the solution was
found to boil at 100.162°C and latm. If the boiling point constant for 100g of water is 5.2.
Calculate the molecular weight of the solute.
(b) The molar volume of liquid benzene ( density 0.877gcm') increased by a factor of 2750 as it
vapourises at 20°C and that of liquid toluene ( density 0.867gcm') increased by factor of 7720
at 20°C. A solution of benzene and toluene at 20°C has a vapour pressure of 46.0torr. Find the
mole fraction of benzene in the vapour above the solution.
11.(a)(i)In calculations involving boiling point elevation and freezing point depressions, molality and
not molarity is used. Explain this observation.
(ii) Explain the significance of Vant Hoff's factor.
(b) 0.008M Na2C204 is isotonic with 0.01M sucrose. Calculate degree of dissociation of Na2C204.
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