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Homework Help: Number Density and pressure

  1. May 30, 2008 #1
    1. The problem statement, all variables and given/known data
    The number density in a container of argon gas is 2.00 X 10^25. The atoms are moving with an rms speed of 455 m/s. What is the pressure inside the container?

    2. Relevant equations
    V rms = sqrt( (3)(k)(T) / m)

    P = F/A = (1/3)(N/V)(m)(v^2 rms)

    3. The attempt at a solution

    I have tried manipulating all the equations to somehow find the pressure, but have been unsuccessful. I seem to have all the variables except the mass. So i assume i need to get the mass somehow, any ideas?

  2. jcsd
  3. May 30, 2008 #2


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    Homework Helper

    What is one mole of gas? What is its volume? What is Avogadro's law?
    Answers to these questions will lead to the mass of the argon.
  4. May 30, 2008 #3
    Is the moles the number density divided by Avogadro's number? And how do i get the volume? I can't use the ideal gas law since i dont have temperature.
  5. May 30, 2008 #4


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    Staff: Mentor

    You have temperature - look at your equations. Still, looks to me like you should consult periodic table.
  6. Jun 30, 2009 #5
    What excatly is "number density" just a fancy way of saying volume seeing as the units are m^3?
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