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Homework Help: Problem with ideal gas pressure

  1. Aug 13, 2008 #1
    1. The problem statement, all variables and given/known data

    Diagram here:
    http://img99.imageshack.us/img99/7189/systemgk9.jpg [Broken]

    Two bulbs, A of volume 100cm3 and B of volume 50cm3 , are connected to a three way tap T which enables them to be filled with gas or evacuated. The volume of the tubes may be neglected.
    Initially bulb A is filled with an ideal gas at 10oC to a pressure of 3.0 x 105 Pa. Bulb B is filled with an ideal gas at 100oC to a pressure of 1.0 x 105 Pa. The two bulbs are connected with A maintained at 10oC and B at 100oC. Calculate the pressure at equilibrium.

    2. Relevant equations
    PV = nRT

    3. The attempt at a solution

    I have the total Volume, total n but I can't find the final temperature of the system.

    I'm learning A-level Physics and this problem comes from a book, the Advanced Level Physics by Michael Nelkon. Please help me. Thank you in advance.
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Aug 13, 2008 #2


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    Initially you have [itex]P_A V_A=n_A R T_A[/itex] and [itex]P_B V_B=n_B R T_B[/itex]. You can figure out all of those numbers, right? Finally you have a new pressure [itex]P[/itex] and new molar numbers [itex]n'_A[/itex] and [itex]n'_B[/itex], three unknowns. So you need three equations to find them. You have two PV=nRT equations in the final state (one for each bulb) and [itex]n_A+n_B=n'_A+n'_B[/itex].
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