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Homework Help: Pressure of outer space

  1. Mar 4, 2006 #1
    I'm trying to calculate the pressure of outer space given the denisty of helium is of the order 1 atom per cm^3, temprature 3K.

    1 atom per cm^3 => 10^6 per m^3.

    It's a low pressure so I guess I can use the ideal gas equation. I also know the mass of a helium atom is 6.68x10^-27 kg.

    What's the best route forward?

    Best Regards, James.
  2. jcsd
  3. Mar 5, 2006 #2


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    Why are you trying to calculate the pressure?

    Either way you can use:
    [tex]pV= nRT [/tex]
    where [itex]n[/itex] is the number of moles and [itex]R = 8.31 J\cdot mol^{-1}\cdot K^{-1}[/itex] and is the molar gas constant.

    You will first need to convert the mass and density into a volume.
    Hope this helps.
    Last edited: Mar 5, 2006
  4. Mar 5, 2006 #3
    That's great. Thanks.
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