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Ideal monatomic gas cycle

  1. Nov 12, 2011 #1
    1. The problem statement, all variables and given/known data

    A 1.00 mol sample of an ideal monatomic gas is taken through the cycle shown in the figure. The process A B is a reversible isothermal expansion where PA = 5.0 atm, PB = 3.0 atm, VA = 30.0 L, and VB = 50.0 L.

    (a) Calculate the net work done by the gas.

    (b) Calculate the energy added to the gas by the heat.

    (c) Calculate the energy exhausted from the gas by heat.

    (d) Calculate the efficiency of the cycle.

    2. Relevant equations

    3. The attempt at a solution
    started by calculating tamp at point A using (pressureA*VolumeA)/number of moles*gas constant, that came to 1822.2K
    then used work=nRT ln(VA/VB) think that came to -7.74kj
    next step W2=PB(VB-VC) which i got 6.06kj as answer

    so net work done 7.74-6.06=1.68

    for the following parts used Q2=n(5/2)R(Tc-Tb) to show energy exhausted
    and Q3=n(3/2)R(Tb-Tc) combined this with W1=Q1 to get energy added

    at some point i have made an error please help
  2. jcsd
  3. Nov 12, 2011 #2
    I agree with the temp you calculated for point A. From A to B is isothermal so the temp along this expansion is 1822K.
    But.... there is no diagram or information about the rest of the cycle!!
  4. Nov 12, 2011 #3
    I also got the work done BY THE GAS in going from A to B to be 7.73kJ.
    This is the amount of heat energy which must be supplied to the gas going from A to B.
    Need the other details of the cycle to complete the calculations.
    You are obviously on the right tracks!!
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