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Homework Help: Thermodynamics problem. Have I answered this correctly?

  1. Jan 31, 2016 #1
    1. The problem statement, all variables and given/known data

    Two rigid containers, A and B, contain the same type of ideal gas and are connected by a thin tube which has been fitted with a valve. The initial pressures of the gases in A and B are P_1 and P_2, respectively, whilst the initial temperatures are T_1 and T_2, respectively. Container B has four times the volume of container A. The connecting valve is fully opened, and a new equilibrium is established whilst the temperature of each container is maintained at its initial value. What is the final pressure in the system?

    2. Relevant equations

    PV = nRT

    3. The attempt at a solution

    PV = nRT

    n = PV/RT

    n_1 + n_2 = n_3

    => (P1 * V1)/R * T1 + (P2 * V2)/R * T2 = (P3 * V1)/R * T1 + (P3 * V2)/R * T2

    => (P1 * V1)/ T1 + (P2 * 4V1)/ T2 = (P3 * V1)/ T1 + (P3 * 4V1)/ T2

    => All the V1's cancel

    => (P1)/ T1 + (P2 * 4)/ T2 = (P3)/ T1 + (P3 * 4)/ T2

    => (P1)/ T1 + (P2 * 4)/ T2 = (P3)(1/ T1 + 4/ T2)

    => Then just solve for P3 by dividing by (1/ T1 + 4/ T2)
  2. jcsd
  3. Jan 31, 2016 #2


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    Science Advisor
    Homework Helper
    Gold Member

    Your answer looks right to me.
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