An equation of state for a fluid composed of particles that have a non-zero volume and a pairwise attractive inter-particle force (such as the van der Waals force). It was derived in 1873 by Johannes Diderik van der Waals who received the Nobel prize in 1910 for “his work on the equation of state for gases and liquids”. The equation is based on a modification of the ideal gas law and approximates the behavior of real fluids taking into account the nonzero size of molecules and the attraction between them.