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Homework Help: Ideal Gas law

  1. Feb 17, 2005 #1
    Consider a high pressure gas cylinder of methane which exhibits a pressure of 200 atmosphers (absolute) at a temp. of 0*C in a small storage building. the building catches fire whcih causes the temp of the cylinder to rise to 1200*C. What would the pressure in the cylinder be then? express your answer in both atmopheres and in psi(lbf/in^2), assume methane behaves as an ideal gas.

    ok. seems easy. but im confused about this whole ideal gas thing. do i always use (0.08205 atmos. liters/ mole K) for R?

    if so then would i do...

    (P1)(V)=(R)(T1) = (200)(V)=(0.08205)(273)
    so, V = ((0.08205)(273))/(200) = 0.1119
    but this number seems unlikley. but if so
    (P2)(V)=(R)(T2) = (P2)(0.1119)=(0.08205)(1473)
    so. P2 = 1080atm? am i doing this somewhat right?
  2. jcsd
  3. Feb 17, 2005 #2
    you don't need to evaluate the volume in this problem, since you don't have the molar number.
    [tex] PV=nRT [/tex] implies [tex] P/T=nR/V [/tex]
    whereas the right hand side is constant... therefore, you have
    [tex] P_{i}/T_{i}=P_{f}/T_{f} [/tex]
  4. Feb 17, 2005 #3


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    The result looks good now pay attention with unit conversion...

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