Methanol, CH3OH, a colorless, volatile liquid, was formerly known as wood alcohol. It boils at 65.0C and has a heat of vaporization of 37.4kj/mol. What is its vapor pressure at 39.0C?
3 answers
Use the Clausius-Clapeyron equation. P at 65.0C = 760 torr. Post your work if you get stuck.
lnP1/P2=3.74X104/8.314(1/312.15-1/338.15)
Not sure what to do from here?
Not sure what to do from here?
You didn't fill in P1 or P2. I gave you P at 65.0 C = 760 torr.
You have let 65 (338K) = T1 so P1 = 760. Solve for P2.
Remember in this type problem that the vapor pressure of ANYTHING at it's boiling point is the pressure of the atmosphere. So if the pressure on Monday is 700 mm Hg, water will boil when it's vapor pressure is 700 mm Hg (which will be well below 100 C, it's normal boiling point). When it appears the problem didn't give you enough information, this is one you pull out of air. P at normal boiling point is standard pressure which, of course, is 760 torr. Make sure P1 goes with T1 and P2 with T2.
You have let 65 (338K) = T1 so P1 = 760. Solve for P2.
Remember in this type problem that the vapor pressure of ANYTHING at it's boiling point is the pressure of the atmosphere. So if the pressure on Monday is 700 mm Hg, water will boil when it's vapor pressure is 700 mm Hg (which will be well below 100 C, it's normal boiling point). When it appears the problem didn't give you enough information, this is one you pull out of air. P at normal boiling point is standard pressure which, of course, is 760 torr. Make sure P1 goes with T1 and P2 with T2.
1 answer