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Homework Help: Work done by product gas in reversible adiabatic expansion

  1. Jan 24, 2015 #1
    • posted in general physics forum, please wait for OP to show work
    I am having trouble calculating the work done by a product gas in reversible adiabatic expansion, and in calculating the final temperature. pV gamma = constant, Cv = constant (assume), gamma = cv + nR / Cv.
    anyone who can help me out?
  2. jcsd
  3. Jan 24, 2015 #2
    Work done = ∫P.dV
    PVγ = P1V1γ = P2V2γ

    Try substituting one equation in the other and integrating from V1 to V2
  4. Jan 24, 2015 #3
    I only know the V1, V2 and n. Should this work or should I assume a P1 of 1 bar?
  5. Jan 24, 2015 #4
    What parameters do you know about the gas in its initial state before the expansion?

  6. Jan 24, 2015 #5
    t is a combustion reaction of ethanol, volume is increasing from 0.02 m3 to 0.04 m3 with a starting temperature of 4000 K. Also the amounts are known. (12g ethane and enough oxygen)
  7. Jan 24, 2015 #6
    You know the initial volume, the initial number of moles of gas, and the initial temperature. From the ideal gas law, what do you get for the initial pressure?

  8. Jan 24, 2015 #7
    Using PV = nRT and PVγ = constant, can you devise an equation with 'V' and 'T'?
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