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Homework Help: Isothermal expansion

  1. Oct 25, 2009 #1
    i was given this test problem a couple of days ago, that ha2 parts:
    1 mol of ideal
    a) isothermal reversible at a Ti, Pi = 3 atm, Pf= 1 atm

    b)irreversible isothermal expansion under constant pressure (1 atm) .

    find the heat/work/internal energy, delta(H), entropy for both.


    part a is easy, that was well covered over the lecture/internets/various physics book

    but for part b, i wasnt so sure

    for my answers i put something in the lines of:

    U = q + w, deltaU = 0
    q = -w
    H = 0 (not too sure)

    i guess since its under constant pressure
    q = -w, and w = -p (delta v)
    q = (1 atm)(Vf - Vi) (volumes were found from ideal gas law)

    and Entropy
    S = Ssys + Ssur
    S = q/t + Ssur

    how do i get the entropy surroundings? and how far off am i?

    edit: bump no love for this thread?
    Last edited: Oct 26, 2009
  2. jcsd
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