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: Free expansion of a Van der Waal's Gas

  1. Feb 1, 2010 #1
    1. The problem statement, all variables and given/known data

    There are two vessels connected by a stopper. Both have the same volume. One has "N_a" moles of gas, the other "N_b". Find the expression for the change in temperature when the stopper is opened and the system is allowed to come to a new equilibrium state.

    3. The attempt at a solution

    I'm supposed to use this equation: [tex] u = C_vT - a/v + const[/tex]

    I tried doing this: [tex]dt/dv = (du/dv) / (du/dt)[/tex] were the denominator is just Cv, but that just gave me:

    [tex]-a/v^2 * 1/C_v[/tex]

    The answer is supposed to look like:

    [tex](2n_an_b - n^2_a - n^2_b)*a/(c_v*2V[n_a + n_b])[/tex]

    How do I get the # of moles into this expression? Thanks.
  2. jcsd
  3. Feb 1, 2010 #2
    Any help please?
  4. Feb 2, 2010 #3
    I am having trouble with this too :S
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook