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Homework Help: Partial Pressure from decomposition

  1. Feb 22, 2007 #1
    1. The problem statement, all variables and given/known data

    An atmospheric chemist fills a gas-reaction container with gaseous dinitrogen pentaoxide to a pressure of 130. kPa, and the gas decomposes to nitrogen dioxide and oxygen. What is the partial pressure of nitrogen dioxide, PNO2, (in kPa) when the total pressure is 166 kPa?

    2. Relevant equations

    2(N2O5) --> 2(N2O2) + 3(O2)


    Dalton's law of Partial Pressure

    3. The attempt at a solution


    Not sure where to start. There is no mention of this in this chapter. I can't use regular gas laws because I am not given any volumes or temperatures.
  2. jcsd
  3. Feb 23, 2007 #2
    Think of an equation that relates partial pressure, mole fraction and total pressure.
  4. Feb 23, 2007 #3


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    Staff Emeritus
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    Looks like "this chapter" is about chemical equilibria.

    Assume volume and temperature are constant - call them V, T. Then how is the total pressure related to the total number of moles of gas in the vessel?

    What exactly happens to the N2O5 that's put into the vessel? What does this do to the total number of moles?
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