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Work done by gas

  1. May 11, 2010 #1
    1. The problem statement, all variables and given/known data

    One mole of a dilute gas initially has a pressure equal to 1.00 atm, and a volume equal to 12.0 L. As the gas is slowly heated, the plot of its state on a PV diagram moves in a straight line to the final state. The gas now has a pressure equal to 5.00 atm, and a volume equal to 76.0 L.

    (a) Find the work done by the gas.
    19.2 kJ [correct]

    (b) Find the heat absorbed by the gas.
    I'm just not sure if I would add Internal Energy and the Work, or subtract the work

    2. Relevant equations

    EQ_18_21.jpg

    Δ U = Q + W
    3. The attempt at a solution

    E = (3/2) nR(T2-T1)
    T1= (P1V1)/nR
    T2=(P2V2)/nR

    T1=((1x10^5)(.012))/R
    T2=((5x10^5)(.076))/R

    Here is where I'm not so sure:

    is it Q= E-W
    -> Q= 36 kJ

    or Q= E+W
    -> Q=74.4 kJ
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. May 11, 2010 #2

    rock.freak667

    User Avatar
    Homework Helper

    Work done by a gas is positive, so you'd add it.
     
  4. May 11, 2010 #3
    Correct, Thank you very much!
     
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