What is the enthalpy of vaporization?

Question

A mixture has a boiling pt of 371.7K with a vapor pressure of 184.52mmhg at 249.55K. what is the enthalpy of vap in kJmol^-1? What is the vap pressure going to be at 295k?

Do I use clausius-clapeyron's equation? I'm not sure how to since I'm missing two variables (p2 and enthalpy of vaporization).

Answer 1

Since the normal boiling point is determined at 1 atm / 760 mm Hg of pressure, this would be P2, or P1 depending on how you want to arrange the Clausius Clapeyron equation. And yes, you can use this equation for this problem.

So try...

ln (760/184.52) = -Ea/0.008314 (1/371.7 - 1/249.55) and solve for Ea

Then use that Ea to solve for the vapor pressure when the temp is 295K