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Homework Help: Respiration pressure problemPlease help!

  1. Mar 29, 2005 #1
    In deep-sea dives the pressure of the air that a diver breathes may be quite large. The mixture of gases breathed is adjusted so that the partial pressure of oxygen is the same as on the surface of the earth. If a person is breathing air with a pressure of 9.1 atm, what % of the molecules in that air should be oxygen in order for the partial pressure(pO2) to be 150 mmHg.

    I think I use F=(p1-p2)/R
    I know atomspheric pressure is 1.013810E5N/m^2
    blood has pO2 of 40 mmHg

    Now of this seems to be going together though.
    Please help...!!!!! Answer should be 2.17%
  2. jcsd
  3. Mar 29, 2005 #2


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    Well,it's not difficult.Think of Dalton's law.Consider 100 molecules of air which are at the pressure of 9.1 atm.Compute how many O_{2} molecules from that air would creat a pressure of 150 mmHg.

    Pay attention to the units.


    P.S.1 atm=101,325 Pa (u don't need it,though).
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