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Equilibrium question

  1. Jun 19, 2005 #1
    A simple question, it would seem, but I'm missing something..
    This is a question in my text.

    Q: Consider a stoppered flask containing benzene, iodine, and air, which has reached equilibrium at 298K. Which one of the following statements concerning the system at equilibrium is true?

    a) The pressure of the vapour phase is not constant.
    b) Evaporation of the liquid continues.
    c) The colour of the liquid phase will change.
    d) The mass of the solid iodine is not constant.

    A: I haven't yet had my text throw me a curveball, but I have found numerous errors which I've confirmed with administrators of the course I'm taking. This one stumps me, which makes me think there's an error. For this one, they all seem untrue. for a), I would think that the pressue of the vapour phase would stay constant unless there were a change in temp. for b) at equilibrium, would evaporation not cease? c) the colour of the liquid will change - obviously not true, since there would have to be a change in temp, or pressure and for d) the iodine would have reached a point of saturation in the benzene at equilibrium, so that couldn't change either...

    Can anyone point out what I'm missing? Any help is greatly appreciated!
  2. jcsd
  3. Jun 19, 2005 #2


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    Write out the balanced equation
  4. Jun 20, 2005 #3
    my guess is that B is the only one that is true. at equilibrium, the liquid will keep evaporating and condensing in the container, and the rates of both will be equal.
  5. Jun 23, 2005 #4


    after spending more time examining the situation, I came to the same conclusion myself. It just required some more thought I suppose.
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