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How much gas is released given partial pressure

  1. Feb 19, 2012 #1
    1. The problem statement, all variables and given/known data
    The solubility of N2 in blood at 37 degree and at a partial pressure of 0.8 atm is 5.6 x 10-4 mol/L?
    a deep sea diver breathes compressed air with the partial pressure of N2 equal to 4 atm. Assume that the total volume of blood in the body is 5 L. Calculate the amount of N2 gas released (in liters at 37 degree and 1 atm) when the diver returns to the surface of water, where the partial pressure of N2 is 0.8 atm


    2. The attempt at a solution

    I got the answer of 0.389, but someone told me it is 0.35. Is my answer correct?
     
  2. jcsd
  3. Feb 20, 2012 #2

    Borek

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    Staff: Mentor

    I got even different value. Please show how you got your result.
     
  4. Feb 23, 2012 #3
    Thanks, the answer is 0.385
     
  5. Feb 23, 2012 #4

    Borek

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    Staff: Mentor

    No!

    At the surface amount of dissolved nitrogen is 5 L * 5.6x10-4 mol/L = 2.78x10-3 mol.

    Under water pressure of the nitrogen is five times larger, so the amount of dissolved gas is also five times larger - that means 5 * 2.78x10-3 mol = 0.0139 mol.

    0.0139 moles of gas at given conditions (1 atm, 37°C) occupies 0.356 L - but it is not the correct answer! That would be the correct answer if all gas were released, but nitrogen dissolves in blood even on the surface. We have already calculated how much will be left dissolved, we have to take it into account.

    Correct answer is below 0.3L.
     
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