As of May 31, 2023, we have updated our Code of Conduct.

Questions with substantial discussion on the behavior of real gases using the van der Waals model (as opposed to just calculations with the van der Waals equation, or a casual reference to the van der Waals model).

Questions/answers with substantial discussion on the behavior of real gases using the van der Waals model (as opposed to just calculations with the van der Waals equation, or a casual reference to the van der Waals model).

(P + an^2/V^2)(V-nb) = nRT as opposed to PV=nRT for an ideal gas

In the van der Waals equation the constant "a" represents a pressure correction. The pressure correction is due to the fact that real gases have intermolecular forces whereas ideal gases should have none.

The constant "b" represents a volume correction. The volume correction is due to the fact that gas molecules have real, non-negligible volumes whereas the ideal gas equation assumes that the volume of the gas molecule is always negligible.