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Homework Help: Adiabatic/Isentropic Compression and Pressure

  1. Oct 18, 2007 #1
    If a piston compresses air (2 moles) to half of its original volume, the temperature increases, according to the gas laws, the volume of the gas will be in step with its temperature. Does this mean that the compressed gas at its new temperature will expand according to its new temperature(say 500 degrees C)?

    For example. If I use the ideal gas equation to check for the potential new pressure,

    t-773 kelvins
    v-1 litre
    p-126 bars.

    So, will 126 bars be the new pressure?

    I cant find this stuff on the net, but i think this is how it works. Can you help clarify?

    Thank you.
  2. jcsd
  3. Oct 13, 2008 #2
    if you try to apply the ideal gas law, PV=nRT, in your original state of one liter, (say at 300K)you only have ,at one atmosphere around ,.041 moles. If you compress the 2 liters adiabatically at.. PxV exp 1.4 , the origianl pressure of one atm increases to 2.6 atm.
    in order for the .041 moles of gas, now occupying 1 liter to exert this much pressure,
    since T=PxV/ nxR then T does in fact= 773K.. you got a pressure of 126 rather than the actual of 2.6 because you used a value of 2 raather than .041 , about a 50 fold difference
  4. Nov 29, 2010 #3
    what are the pv diagrams of an isentropic process??
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