Question

Biphenyl, C12H10, is a nonvolatile, nonionizing solute that is soluble in benzene, C6H6. At 25 °C, the vapor pressure of pure benzene is 100.84 torr. What is the vapor pressure of a solution made from dissolving 10.5 g of biphenyl in 34.2 g of benzene?

Answer 1

Moles of biphenyl = 10.5 g/130 g/mol = 0.0808 mol Moles of benzene = 34.2 g/78 g/mol = 0.439 mol Mole fraction of benzene = 0.439 mol/0.439 mol + 0.0808 mol = 0.845 Vapor pressure of solution p_sol = mole fraction of benzene times vapor pressure of pure benzene = 0.845 times 100.84 torr = 85.21 torr