Gasoline is a complex mixture of hydrocarbons, including different isomers of octane. Gasoline is sold with a variety of octane ratings that are based on the comparison of the gasoline with the combustion properties of isooctane, a structural isomer of c8h18. The structure of isooctane and another isomer of c8h18 are shown in the figure below, along with their normal boiling points and heats of vaporization. Determine the vapor pressure of each isomer on a very hot summer day, 38. 0 °c.