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I Introducing two identical containers with different gasses

  1. Mar 31, 2017 #1
    If you have two different containers filled with two different gasses at the same temperature, would they have less pressure when connected to each other?
    Dalton's law states that each of the gases behave independently when it comes to pressure as they fill the space as if they were the only gas occupying it.

    So, my thought is trying to understand a concept of this in action. If I have two tanks hooked together holding the same pressure and temperature with different gasses. When I open them to each other, will the individual gasses then expand throughout the now bigger volume, and each have a lower partial pressure?

    The way this is always explained seems like this would be the case. I have a very hard time believing it, and am hoping that I am hopelessly wrong and one of you out there knows how this would really work.
    Last edited by a moderator: Mar 31, 2017
  2. jcsd
  3. Mar 31, 2017 #2


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    The containers would not have less pressure. The gases, as you say, would diffuse throughout the whole volume, in which each gas would have a partial pressure lower than their initial pressure, but the total pressure would be the same as before. For example, if two identical containers held oxygen and nitrogen at 1 atm and 298K, when they were connected and allowed to mix, the total volume would contain a mixture of oxygen and nitrogen, each with a partial pressure of 0.5 atm, and a total pressure of 1 atm.
  4. Mar 31, 2017 #3

    You, Sir, are a gentleman, and a scholar. Mind=BLOWN!

    Follow up question, if you are up for it, does this mean that increasing the moles of gas A would not increase the pressure of gas B? Such as, if I put more oxygen in the container, the nitrogen would be unaffected in terms of compression?
  5. Apr 3, 2017 #4


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    Well, if the oxygen was initially at 2 atm and the nitrogen at 1 atm, after mixing thepartial pressure of oxygen would be 1 atm and nitrogen 0.5 atm, total pressure 1.5 atm. So no, the partial pressure of the nitrogen would not be affected by increasing that of oxygen.
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