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Easy Temperature and Kinetic Throey Problem

  1. Nov 7, 2007 #1
    If 2.4m^3 of a gas initially at STP is compressed to 1.6m^3 and its temperature is raised to 30degreesC, what is the final pressure?

    I thought this would be a easy one but my answers are coming out and dont look right.

    I used pV=nRT

    p=1.6m^3
    V=2.4m^3
    R=8.31J(mol*k) --- universal gas constant
    T=30degreesC

    So I plugged everything into the equation pV=nRT and solved for n and got .015403, it didnt look right so I converted 30degreesC to K (which equals 303.15K) then solved for n again and got .00154, which im sure is also wrong.

    Am I using the wrong equation?? There was only a few to choose from in the book:

    pV/T=Constant, pV=nRT, pV/T=NKsubB

    Please Help thanks
     
  2. jcsd
  3. Nov 7, 2007 #2
    if you look at what you are given you have Po, Vo, To. Then we know it is compressed and the temp raises so we know T and V after. We have to solve for P. from the equations below theres one that uses those 3 variables.
     
  4. Nov 7, 2007 #3
    Im assuming pV/T=constant, because the other two deal with molecules.

    so p(2.4m^3)/30=1.6m^3?
     
  5. Nov 7, 2007 #4
    PV/T = constant (nK) and that works for both initial and final. Now you'll have two equations with two unknowns, Tfinal and constant

    you also know initial pressure, initial volume, and initial temperature so you can find what the constant equals
     
    Last edited: Nov 7, 2007
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