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Homework Help: Mass-volume-pressure relationship

  1. Jul 19, 2008 #1
    1. The problem statement, all variables and given/known data
    What is the volume of a sample of oxygen gas has a mass of 50 grams and is under pressure of 1.20 atm at 27 degrees celsius?

    3. The attempt at a solution

    Density = Pressure(in pascals)/(specific gas constant * Temperature (in kelvins))

    1 atm = 101,325 pascals ~ 1.2 atm = 121,590 pascals
    27oCelsius = 300.15 K

    Density = (121,590 pascals)/(8.314 * 300.15 K) = 48.72 kg/m3 = 48,720 g/m3

    48,720 g/m3 = 50 g/V ~ V = 1.03 x 10-3 m3
     
  2. jcsd
  3. Jul 19, 2008 #2
    Hint: Ideal Gas Law (PV = nRT)
     
  4. Jul 20, 2008 #3
    So... (1.2 atm)(V) = (3.13 mol)(8.314)(300.15 K) ~ V = 6509 L??
     
  5. Jul 20, 2008 #4
    Not quite --
    1) Oxygen is a diatomic gas (O2)
    2) Check your units -- your gas constant (and consequently the volume) is off by (about) two orders of magnitude!
    _For your units, the gas constant is approximately 0.0821 L*atm/(K*mol)
     
  6. Jul 22, 2008 #5
    (1.2 atm)(V) = (1.56 mol)(0.0821)(300.15 K) ~ V = 32.09 L?
     
  7. Jul 24, 2008 #6
    yes, that is correct
     
  8. Jul 19, 2010 #7
    Hi, can someone please help me...its quite urgent....I have two vessels, one has capacity of 0.5l and the other 0.15l. The 0.15l is in a vacuum state held constantly at -80C and the 0.5l vessel is at 50mbar at room temperature (20C). I have gas in the 0.5l vessel......I then open the valve and release the gas to the vacuum upon which it immediately desublimes.. until it reaches equilibrium state and then i close the valve and take the smaller vessel away. What conditions hold at equilibrium??? and how do I find the mass of desublimed solid???
     
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