1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Clausius Clapeyron Equation

  1. Nov 17, 2013 #1


    User Avatar
    Gold Member

    1. The problem statement, all variables and given/known data

    Determine the vapor pressure of water at 50 degrees C. The molar heat of vaporization of water is 40.7 kJ/mol.

    2. Relevant equations

    Clausius-Clapeyron equation.


    3. The attempt at a solution

    P1 = 760 mm Hg
    T1 = 373 K

    P2 = ?
    T2 = 323 K

    ln (P2/760) = ln P2 - ln 760 = -(40700/8.31)(1/323 - 1/373). I'm taking the change in temperature (delta T, or final minus initial temperature, and accordingly I put a negative out in front of the right side of the equation).

    ln P2 = 4.6

    e^4.6 = P2 = 100 mm Hg (approximately).

    Is this correct?
  2. jcsd
  3. Nov 17, 2013 #2


    User Avatar

    Staff: Mentor

    Tables give 92.51 mm Hg, so you are reasonably close.
  4. Nov 17, 2013 #3


    User Avatar
    Gold Member

    Thank you :-)!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted