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!

Proof for la grangian

  1. Feb 5, 2012 #1
    As this thread implies i wanted to try to prove ideal gas equation pV=vnRT

    where T is tempearture p is pressure n is mole V is volume and R is gas constant

    and then I found that I had to prove la grangian

    What I wonder about is given in thread here


    In the end of the thread it is said that someone her might be able to help me with a suitable textbook. Is that possible?
  2. jcsd
  3. Feb 5, 2012 #2
    Hello Georg,

    As with strangerep in the other thread you started I am not sure what you are attempting, but you should look up the Joule experiment and the Joule-Thompson experiment.

    They proved experimentally that the so called internal pressure of an ideal gas is zero.

    This provides an alternative definition of an ideal gas as a gas with

    [tex]{\left( {\frac{{\partial U}}{{\partial V}}} \right)_T} = 0[/tex]

    You can use this plus Boyle's law to derive PV=NRT.

    The following thermodynamic relation is also useful. this relates to all substances, not only ideal gasses.

    [tex]{\left( {\frac{{\partial U}}{{\partial V}}} \right)_T} + P = T{\left( {\frac{{\partial P}}{{\partial T}}} \right)_V}[/tex]

    By the way did you see my answer in your other thread about reversibility?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook