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Homework Help: Ideal Gas Law- finding gas density

  1. Feb 16, 2009 #1
    1. The problem statement, all variables and given/known data

    What is the density of radon gas at 0 degrees C and 1 atmosphere?

    2. Relevant equations

    PV= nRT
    0 C = 273 K

    density = mass/volume g/m^3

    3. The attempt at a solution

    I want density = g/m^3

    Below are the units of PV = nRT. I thought that breaking it down would help me to see where the g's and the m^3 are- but so far its just confused me.


    I have been trying to manipulate PV = nRT so that the units eventually give me g/m^3. I think I got something close, but then realized that all I have to plug in is T and P. This is what I tried: P/R = nT/V Units end up: g/m^3 = 1/m^3 I'm not sure if that works out...

    Nothing is changing so I can't cancel anything and then set up a proportion equation- What the heck do I do??
  2. jcsd
  3. Feb 16, 2009 #2

    Andrew Mason

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    Science Advisor
    Homework Helper

    You won't find the answer with just PV=nRT. This is because mass of the gas molecules has no effect on P, V or T for an ideal gas.

    Since density is mass/volume you need to relate mass to volume. What is the number of molecules per unit volume? What is the mass of a molecule of Radon gas?

  4. Feb 17, 2009 #3
    Thanks so much!!! I worked it out then referenced to the actual density of radon that I found online and it agrees :wink:

    Thanks again AM.
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