Question

The boiling point of ethanol is 78.5C and delta H vap = 40.5kJ/mol. Calculate the vapor pressure (in torr) of ethanol at 0.0C ?

Answer 1

Use the Clausius-Clapeyron equation. The vapor pressure of ANY substance at its boiling point is atmospheric pressure, so if we assume standard conditions, the vp of ethanol at its boiling point will be 760 mm Hg. Don't forget to use Kelvin for temperature.