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I've read that the behaviour of ideal gases is approximated really well by that of the noble Gases at high temperatures and low pressures. Suppose we manage to put some atoms of a noble gas into a sealed and evacuated cube. Are the collisions between the atoms going to be elastic? Are there going to be interaction between atoms? I would like to know exactly, what are the main differences, if there are any, as well as what is negligible, if it's not all.

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    $\begingroup$ The biggest difference will be that real gas atoms (including noble gases) have a real volume - they are not point particles. So, that changes the ideal gas law by a little bit. In the Van der Waals gas equation, this is usually the constant 'b', in P(V-b). $\endgroup$ – Jon Custer Jun 29 '17 at 15:10
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Noble gases are especially good approximations of an ideal gas because they are monatomic and interact only by van der Waals forces, which unfortunately (and especially with larger noble-gas atoms) affect any gas to some extent. See here for a model that tries addressing this. Helium is least susceptible to these concerns. However, quantum effects will be important at low temperatures; for example, helium-3 is much more ideal than is helium-4, which enters an Einstein-Bose condensate.

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