# Concept Revisor : Solutions

Chemistry Level 4

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 $$5.5 ^{ \circ } \text{C}.$$
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