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Homework Help: Ideal Gas Equation

  1. Mar 6, 2005 #1
    Having written about ideal gases, I now have to say to what extent the ideal gas equation of state is an expression of experimental results, and to what extent a definition.

    My instant reaction is to say it is fully based on experimental results, having been derived from the results of Boyle's law , Charles' law and the perfect gas law. It also relies on Avogadro's result that the consant R is the same for one mole of any gas.

    I'm not really sure it's right to say the equation is not a definition though. I suppose that given some values for the quantities involved, then it defines the other quantity for an ideal gas?

    Any suggestions? Thanks :smile:
  2. jcsd
  3. Mar 6, 2005 #2

    Andrew Mason

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    The ideal gas law was derived from theory and observation, but it is an approximation, like many 'laws' in physics. It doesn't take into account the electrical forces between molecules nor does it take into account the space taken up by the molecules themselves.

    Van de Waals developed a modified gas equation that improved it greatly by taking into account these factors. ( P + a/V2 )( V - b ) = RT. Thiis was a refinement based on theory and gave results that agreed much better with experiment.

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