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Homework Help: Thermodynamic query

  1. May 4, 2015 #1
    one gram molecule of monoatomic gas is taken at s.t.p. keeping its volume constant,its temperature is raised by 1k. one gram molecule of the gas is added isothermally to this.the mixture is now cooled by 1k at constant volume to return to s.t.p. if [c][/v] be gram molecular specific heat of gas constant volume, net heat transfer in the whole process is??

    my solution: for 1st step- w=o,q=u=n[c][/v]dt=[c][/v]
    2nd step-i dont know what will be q=?..as u=0, q=w, but how to find w?
    3rd step-q=2[c][/v]
  2. jcsd
  3. May 5, 2015 #2
    What is the volume occupied by one gram molecule of a gas at s.t.p?
    When you add some more gas, what happens to P, V, T? (T is constant since process is isothermal).
    Once you have have found final volume, then use ##W=\int PdV##
  4. May 5, 2015 #3
    This is a very poorly defined problem. You are not told how the two gases are combined. It could be at constant pressure, for all we know. That is the simplest case to consider.

  5. May 5, 2015 #4
    volume at stp. is 22.4l. since we add 1mole gas it becomes 44.8l then should i use w=nrtlogv2/v1 (work done is isothermal process).
    but if i use this answer is not coming.
    i also thought that q=msdt and since temperature in second step is constant so q=0. is this correct??

    the answer given is 3[c][/v].
  6. May 5, 2015 #5
    i am sorry but this is how the question was given in my book
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