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Finding Max Volume for evaporation need help

  1. May 10, 2014 #1
    So this is the problem that I am working on. It is a woosh bottle where I am inputting 70% isopropyl alcohol, closing the top and waiting for the alcohol to evaporate. This mixture is then ignited to generate a flame. My job for this project is to calculate the maximum volume of 70% isopropyl alcohol where all of the alcohol evaporates.
    Here hows I attempted to solve the problem
    Then I just started writing up equations
    V=Vliq+Vgasinit %I am saying that the inital amount of gas in my 2L bottle plus the volume of the alchol is equal to the total volume in the container.
    Pinit*Vgasinit=n(init)*R*T %Perfect gas law for the container originally
    n(init)=n(O2)+n(N2) %The has is just oxygen and nitrogen as first (air)
    n(final)-n(water)-n(alcohol)=n(init) %The number of moles after the fuel has evaporated and come to equilibrium with air
    n(final)=n(alcohol)+n(H2O)+n(O2)+n(N2) %The n alcohol is the 70% of the isopropyl and 30% is water which is where I got the n(H20)
    I been looking at this problem for hours and can seem to figure out where to go. With the amount of equations I have made up, I have way morre unknowns than equations. Is there something to do with raoults law that I can do or this problem just not possible with the amount of information that I know.
    Any help would really be appreciated.
  2. jcsd
  3. May 27, 2014 #2
    I'm sorry you are not generating any responses at the moment. Is there any additional information you can share with us? Any new findings?
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