Acetone has a delta Hvap of 29.1 kj/mol and a normal boiling point of 56.2 degrees Celsius. At what temperature (in degrees Celsius) does acetone have a Pvap = 118 mm Hg?

Answer 1

Use the Clausius-Clapeyron equation.
ln(p2/p1) = (dHvap/R)(1/T1 - 1/T2)
Substitute 29,100 for dHvap, 56.2 for T1 and 760 mm for p1. Then solve for T2 when p2 = 118. I've used celsius for both temperatures; don't forget to change them to kelvin before substituting.