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Compressed reversibly and adiabatically problem

  1. Jun 6, 2005 #1
    hey, i was wondering if anyone could help with this question. it seems simple but i cant find a formula for it.
    2.5 mol of perfect gas at 220 K and 200 kPa is compressed reversibly and adiabatically until the temperature reaches 255 K. Given that its molar constant-volume heat capacity, CV,m, is 27.6 J K-1 mol-1, calculate the final volume in L.
    many of the equations i have come across need atleast the initial volume so i tried to work out initial volume by pV=nRT which.. gave me an initial voume of 2316.77L

    next i used Tf/Ti=(Vi/Vf)^(1/c)
    but i got a final answer of 3782L
    its a pretty big answer and iit was incorrect.. could someone pls help..
    p.s i also tried to work out the final pressue in kPa and also deltaH.. without any luck. any help would be great!
  2. jcsd
  3. Jun 6, 2005 #2
    You are wrong even with your initial volume. Just show your calculations so that we can say where you went wrong. For final volume, you should first get the ratio of specific heats. Find out the formula for the relation between specific heats and gas constants. Rest of the things will be easy.
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