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Homework Help: Merging two chambers of identicle gas

  1. Jul 24, 2010 #1
    1. The problem statement, all variables and given/known data
    Two samples of the same ideal gas, x and y, are in adjacent chambers, separated by a thermally insulating partition. The initial volumes, pressures and temperatures of the samples are, Vx, Vy, px, py and Tx, Ty. The partition is removed and the single chamber is brought to a final temperature Tf. If the volume occupied by the partition is negligible, what is the final pressure? (Express your answer in terms of Vx, Vy, px, py and Tx, Ty
    and Tf)

    2. Relevant equations
    Pv = nRT?

    3. The attempt at a solution
    I honestly have no idea how to even start this one sorry :/
  2. jcsd
  3. Jul 24, 2010 #2


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    What does n stand for in that equation?
    Perhaps you can apply it first to x and y separately and solve for n?
  4. Jul 24, 2010 #3
    n is the number of moles in the camber
    for x: [tex]n = \frac{P_xV_x}{RT_x}[/tex]
    for y: [tex]n = \frac{P_yV_y}{RT_y}[/tex]

    for the new camber (merged): [tex]n = \frac{P_yV_y}{RT_y} + \frac{P_xV_x}{RT_x}[/tex]

    so [tex]T_f = \frac{P_f(V_x + V_y)}{(\frac{P_yV_y}{RT_y} + \frac{P_xV_x}{RT_x})R}[/tex]

    but then i still cant get Tf as i don't know pf (pressure in joined container)
  5. Jul 24, 2010 #4


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    You are almost there. Please re-read the question carefully. What is your target variable, and which variables should you express it in?
  6. Jul 24, 2010 #5
    oh i was trying to find the wrong thing ^^ oh its easy then thankyou
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