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Homework Help: Composition Determination

  1. Apr 4, 2010 #1
    Hello, I have been given the following problem and am hoping for some help....

    You have 1000 unlabeled gas cylinders, each are 0.25m3 and need to be able to identify the contents. They mostly contain oxygen and helium, but some contain xenon and uranium hexafluoride. You are given a scale, pressure gauge, unlimited water, bubble gum, duct tape, ice, firewood and matches. You are also given a "fugacity meter" and use of a thermodynamics textbook..

    So, using just those items, how can you determine what the cylinders contain?

    For bonus points, any use of the Maxwell relations are to be used.

    So, if anyone's got any ideas, please help me out :)
     
  2. jcsd
  3. Apr 4, 2010 #2

    berkeman

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    Staff: Mentor

    Yoiks. It seems the scale is the most practical device...?
     
  4. Apr 4, 2010 #3

    berkeman

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    Staff: Mentor

    Do you have any ideas?
     
  5. Apr 4, 2010 #4
    I was thinking something along the lines of placing all the cylinders in the water, since that'll make sure they're all the same temp. Then measure the pressure, and fugacity at this point. Then you could add ice until the ice stops melting, but before the whole thing crystallizes, which will be around 0 C and measure the pressure and fugacity again. Then you could heat it up using the firewood until the water begins to boil, which will be 100C obviously... Measuring the pressure and fugacity here again. Then you could do something with the partial derivatives of fugacity relating to temperature. But I'm not sure exactly where to go with that.. Or likewise, partial derivatives of pressure relating to temperature..
     
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