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A question of the Intercompatibility of the Gas Laws.

  1. Aug 26, 2009 #1
    I was recently taught about the three gas laws:

    1)Boyle's Law, which stated that pressure is inversely proportional to volume and vice-versa at a constant temperature.

    2)Charle's Law, which stated that volume is directly proportional to temperature at a a constant pressure

    3)Amonton Law, which stated that pressure is directly proportional to temperature at a constant volume.

    I have no confusion regarding the first two laws, but, I don't understand how increasing temperature would increase pressure (Amonton's Law) unless the gas is in an enclosed container (so that when it's temp. is increased, it's volume increases too, which will cause it's molecules to collide with the container more often to produce more pressure).
    If we consider Amonoton's Law to be in the context of a closed container, then Boyle's Law and Charle's Law would also be in the context of a closed container (because the three laws are used together to derive the gas equation PV=nRT). But, then Boyle's Law would make no sense.
    So, the three laws are not intercompatible, which means the gas equation is wrong .... but ... how??
  2. jcsd
  3. Aug 26, 2009 #2
    Your perspective about the pressure is totally right, but you've overlooked the fact that you're studying the gas not the container that contains the gas. When you want to study the gas, you put it in different containers and in different circumstances and watch how it'll act in every environment, so you can give a general law for it everywhere in any situation.
    Eventually, you can combine everything you saw in 1 law that tells you everything you want in every environment, which means that the general law (ideal gas law) should agree with the 3 partial laws you've seen in the experiment, which is the case in in the ideal gas law PV=nRT when you set any of the 3 variables to be a constant.

    If this answer doesn't convince you, ask again and you're welcome :)

    Good luck :)
    Last edited: Aug 26, 2009
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