What are the limitations of the Ideal Gas Law?

[optrix]

I've been looking at Charles law, Boyles law, the Pressure law, and the Ideal gas law, PV=nRT. I want to know, what limitations are there to the gas law? Basically, why aren't real gasses ideal, when isn't it possible to use the ideal gas law, and in such a case, what else do you have to use instead? Thanks a lot.

 

[kkrizka]

For ideal gases, we are assuming that there are no intermolecular forces and that the molecules themselves take up no volume. This is quite true at low pressures, because the spacing between the molecules is so large that they rarely collide. Also low pressure usually means that there is little of them or that the volume of the container is very large, so the space taken up by the actual molecules is negligible.

If you are dealing with cases where this is not true, you use the Van der Waals equation:
http://en.wikipedia.org/wiki/Van_der_Waals_equation

 

[optrix]

Thanks for the help!