Chapter 13, Problem 13.108SP

Hepatane $({\text{C}}_{\text{7}}{\text{H}}_{\text{16}})$ and octane $({\text{C}}_{\text{8}}{\text{H}}_{\text{18}})$ are constituents of gasoline. At 80.0^oC, the vapor pressure of heptanes is 428 mm Hg, and the vapor pressure of octane is 175 mm Hg. What is ${\text{X}}_{\text{heptane}}$ in a mixture of heptanes and octane that has a vapor pressure of 305 mm Hg at 80.0 ^oC?