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Homework Help: Thermodynamics - Work

  1. Apr 9, 2010 #1
    1. The problem statement, all variables and given/known data
    Consider a reversible isothermal expansion of two moles of CO2 from 1 L to 60 L at 298 K. Assume that CO2 obeys an equation of state P = nRT/(V − nb) − n2a/V 2 with b = .04286 L mol−1 and a = 3.658 L2 bar mol−2.
    (a) Calculate W.

    2. Relevant equations

    P = nRT/(V − nb) − n^(2)a/V^2

    3. The attempt at a solution
    dW = -PextdV
    W = -P[(int from V1 to V2)dV
    = -P(60L-1L)
    My issue here is, I dont know how to find P. The Van der Walls gas equation is posted above, my only issue is I dont know which V to use... Initial? Final? The difference of the two?
    Thanks for the help!
  2. jcsd
  3. Apr 10, 2010 #2

    jack action

    User Avatar
    Science Advisor
    Gold Member

    P is a function of V (the one given in your problem). You have to integrate THAT function from 1 L to 60 L.
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