Updated on August 6, 2022
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 12.8 g of biphenyl in 27.0 g of benzene?
vapor pressure in torr
(12.8 g C12H10) / (154.21 g C12H10/mol) = 0.083004 mol C12H10
(27.0 g C6H6) / (78.11 g C6H6/mol) = 0.34567 mol C6H6
Supposing the mixture in question to be at 25 °C:
(100.84 torr) x (0.34567 mol C6H6) / (0.34567 mol + 0.083004 mol) = 81.3 torr