1. The problem statement, all variables and given/known data A handbook lists the normal boiling point of isooctane, a gasoline component as 99.2°C and its enthalpy of vaporization as 35.76 kJ/mol. Calculate the vapor pressure of isooctane at 25°C. 2. Relevant equations The only equation that makes sense to use for me is the Clausius-Clapeyron equation: ln(P2/P1) = (Hvap)/R * (1/T1 - 1/T2) 3. The attempt at a solution Since I don't have either P2 or P1, how can I solve this problem? Should I just isolate (P2/P1), and solve?