Concept Revisor : Solutions

The molar volume of liquid benzene with density $\rho = 0.877\text{ g/ml}$ increases by $2750$ times as it vapourises at $20^\circ\text{C}.$

At $27 ^{ \circ } \text{C}$ when a non-volatile non-dissociating solute is dissolved in $54.6\text{ ml}$ of benzene, the vapour pressure of the solution is found to be $98.88\text{ mmHg}.$

Calculate the freezing point (in degrees Celsius) of the solution.

Details and Assumptions

• The enthalpy of vapourisation of liquid benzene is $394.57\text{ J g}^{-1}.$
• The enthalpy of fusion of liquid benzene is $10.06\text{ kJ mol}^{-1}.$
• The freezing point of pure benzene is $5.5 ^{ \circ } \text{C}.$