Two alcohols, isopropyl alcohol and propyl alcohol, have the same molecular formula, C₃H₈O. A solution of the two that is two-thirds by mass isopropyl alcohol has a vapor pressure of 0.110 atm at 313 K. A solution that is one-third by mass isopropyl alcohol has a vapor pressure of 0.089 atm at 313 K. Calculate the vapor pressure of each pure alcohol at this temperature.

Explain the difference given that the formula of propyl alcohol is CH₃CH₂CH₂OH and that of isopropyl alcohol is (CH₃)₂CHOH.