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Change in internal engergy of a monatomic ideal gas

  1. Nov 17, 2009 #1
    1. The problem statement, all variables and given/known data
    A monatomic ideal gas expands from 1.00 meters cubed to 2.50 meters cubed at a constant pressure of 2.00 x 10^5 Pa. Find the change in the internal energy of the gas.



    2. Relevant equations

    [tex]\Delta[/tex]U = Q + W

    3. The attempt at a solution

    Well, I know how to find work, which is -P[tex]\Delta[/tex]V

    But I'm having trouble finding the energy transferred into the system by heat, or Q, because the problem does not give a specific value for it.

    I would much appreciate it if someone could give me some pointers as to how to find Q.
     
  2. jcsd
  3. Nov 17, 2009 #2

    kuruman

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    How is Q related the the specific heat at constant pressure?
     
  4. Nov 17, 2009 #3
    I don't exactly know, I do know that [tex]\Delta[/tex]U = 3/2nR[tex]\Delta[/tex]T for a monatomic gas, where the molar specific heat is given by Cv = 3/2R
     
  5. Nov 17, 2009 #4

    kuruman

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    If you know CV, then Cp = CV + R. Also at constant pressure Q = n CpΔT. Now you can put it together.
     
  6. Nov 18, 2009 #5
    Aha, thanks for the help! I got it.
     
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