(A) The vapor pressure of pure hexane and pentane at 25 °C are 149.1 mmHg and 508.5 mmHg, respectively. If a hexane–pentane solution has a mole fraction of hexane of 0.750, what are the vapor pressures of hexane and pentane above the solution? What is the total vapor pressure?

(B) Calculate the vapor pressures of benzene, C₆H₆, and toluene, C₇H₈, and the total pressure at 25 above a solution with equal masses of the two liquids. Use the vapor pressure data given in Example 14-6.

Example 14-6

The vapor pressures of pure benzene and pure toluene at 25 °C are 95.1 and 28.4 mmHg, respectively. Asolution is prepared in which the mole fractions of benzene and toluene are both 0.500. What are the partial pressures of the benzene and toluene above this solution? What is the total vapor pressure?