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Homework Help: Ideal Gas Law (Simple )

  1. Sep 9, 2007 #1
    1. The problem statement, all variables and given/known data

    I need to find the volume for 1 kg of diatomic oxygen for a pressure of 150,000 Pa and a temperature of 100K. This is really part of a larger project, and I need to make sure I'm not tripping up on little details. It's that 1 kg of diatomic oxygen that I am a bit unsure about, or just plain having a brain freeze about.

    R* = 8.314 J/K*mol
    T = 100 K
    P = 150,000 Pa
    n = ??

    2. Relevant equations

    PV = nRT

    3. The attempt at a solution

    Solving the equation for V; V = nRT/P. No big deal. My problem is making sure I have the correct n in the equation. The mass of diatomic oxygen is 32.0 grams, which is what I was using in my solutions. However, I realize that I have 1 kg of O2, not 1 g of it. Should I really be using 32,000 for my n? Or something else?
  2. jcsd
  3. Sep 9, 2007 #2
    you're using the wrong R constant. i'm working on it right now.
    Last edited: Sep 9, 2007
  4. Sep 9, 2007 #3


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    Homework Helper

    You haven't properly converted mass to moles. Check that your units make sense in your calculation.
  5. Sep 9, 2007 #4


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    Staff Emeritus
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  6. Sep 9, 2007 #5
    Thanks, everyone.

    If I am looking at this all correctly, since I have 1 kg of diatomic oxygen, my number of moles should be: 1000 g / 32.00 g, which gives me my number of moles (n) equal to 31.25. Am I on the right track now?
  7. Sep 9, 2007 #6
  8. Sep 9, 2007 #7
    Thanks for the help, everyone!! It was a total brain freeze on my part...
  9. Sep 9, 2007 #8
    what was your final answer?
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