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Ideal gas law problem?

  1. Feb 2, 2014 #1
    A spherical helium balloon 11 m in diameter is at ambient temperature and pressure, 15 degrees Celsius and 100 kPa. How much helium does it contain? It can list a total mass of balanced atmospheric air. How much mass of the balloon fabric & cage can then be lifted?

    Here is my work but I'm unsure if it's correct. If someone could let me know I would really appreciate it. I also don't know how to answer the second part of the problem at all. Thanks in advance!

    r = 5.5 m
    T = 15°C = 288.15 K
    P = 100 kPa = 100 kN/m
    R = .287 kN m/kg K

    m = PV/RT = 842.69 kg Helium
  2. jcsd
  3. Feb 2, 2014 #2


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    You seem to have hybridised two formulae:
    PV = mRspecT
    PV = nRT
    where m is mass, n is number of moles, and Rspec is a constant specific to the gas.
  4. Feb 2, 2014 #3
    What did you get for the volume of the balloon?

    Does it really make sense to you that a balloon of this volume can hold close to a metric ton of helium at atmospheric pressure?

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