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Homework Help: Thermodynamics question. Could be simpler than it looks, but I am really stuck.

  1. Aug 26, 2010 #1
    Precisely what does the following equation, in which R is the gas constant, allow one to calculate?



    ln xs = -dHf/R(T0-T/TT0)



    I have no idea what this could be. I know what each part of the equation is (gas constant, change in enthalpy of formation, Freezing point depression etc.) I just don't know what it allows me to calculate...except that its the natural log of something. I think it has something to do with entropy, but I'm not sure. Any help would be much appreciated.
     
    Last edited: Aug 26, 2010
  2. jcsd
  3. Aug 27, 2010 #2

    presbyope

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    Notation is ambiguous. Did you mean

    [tex]
    \ln x_s = \frac{-dH_f}{R}\left(\frac{T_0-T}{TT_0}\right)
    [/tex]

    in which case [itex]x_s[/itex] is dimensionless?
     
  4. Aug 29, 2010 #3
    That is exactly what I meant, yes. I did not know you could put in equations like that. Anyway, I have to find out precisely what it allows me to calculate, but I have no idea.
     
  5. Aug 29, 2010 #4

    presbyope

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    Try this:
    1. the expression with T can be rewritten as two terms
    2. exponentiate
     
    Last edited: Aug 29, 2010
  6. Aug 29, 2010 #5

    presbyope

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    That should give you something that looks a lot like something else you're familiar with :-/
     
  7. Aug 30, 2010 #6
    Oohhhhh yeeeah! Thanks for that!
     
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