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Help with the pressure problem

  1. Jan 23, 2009 #1
    i need help with this two problems

    1. The problem statement, all variables and given/known data

    calculate the pressure of 3.2gm of O2 gas in acontainer its volume 4000ml at 100oC knowing that the molucul mass for O2 = 16u


    2. Relevant equations



    3. The attempt at a solution

    PV=nRT
    P=3.2x8.314x373x1000000 /(16x2x4000 )


    1. The problem statement, all variables and given/known data

    At atmospheric pressure and at 0oC and the molecule mass for Nitrogen is 28 u so the volume for 1Kg mol equal


    2. Relevant equations



    3. The attempt at a solution

    PV=nRT
    V = 273x8.314 /28x1.o13x105
     
  2. jcsd
  3. Jan 23, 2009 #2

    LowlyPion

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    Welcome to PF.

    What do you seem to be having trouble with?

    What units are your answers supposed to be?
     
  4. Jan 23, 2009 #3
    I just want to know if my answer in correct


    for the first problem 'Pa' and the second 'm3/Kg mol'
     
  5. Jan 23, 2009 #4

    LowlyPion

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    The first one looks like it is set up OK for Pa.

    Volume though is generally given as m3 or L.

    I'm not sure what you mean by "m3/Kg mol"
     
  6. Jan 23, 2009 #5
    so it is o.k if i just used m3 right ..??


    thanks for your help
     
  7. Jan 23, 2009 #6

    LowlyPion

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    I'd say it is set up OK for finding the volume of 1 kg of N gas, if that is the question.

    But I hesitate with your statement "the volume for 1Kg mol equal "
     
  8. Jan 23, 2009 #7
    sorry I'm lost here ..
    you mean if the question says the volume of 1 kg of N gas then m3 is correct, but what about is the question says the volume for 1Kg mol equal then is it o.k if i used m3/Kg mol or not ..
     
  9. Jan 23, 2009 #8

    LowlyPion

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    I was merely pointing out that the statement of the problem is suggesting something different.

    1 kg mol of a substance is 1kg*Molecular mass.

    So for your problem with Nitrogen at 28, this suggests that you would use 28 kg of gas, not 1 kg.

    Your answer looks to me like it's off by a factor of 28.
     
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