Van der Waals , Johannes Diderik

(1837–1923) Dutch physicist

Van der Waals was born at Leiden in the Netherlands. He was largely self-taught in science and he originally worked as a school teacher. He later managed to study at the University of Leiden, having been exempted from the Latin and Greek entrance requirements. In 1877 he became professor of physics at the University of Amsterdam.

Van der Waals studied the kinetic theory of gases and fluids and in 1873 presented his influential doctoral thesis, On the Continuity of the Liquid and Gaseous States. His main work was to develop an equation (the van der Waals equation) that – unlike the gas laws of Robert Boyle and Jacques Charles – applied to real gases. The Boyle–Charles law, strictly speaking, applies only to ‘ideal’ gases, but can be derived from the kinetic theory given the assumptions that there are no attractive forces between gas molecules and that the molecules themselves have zero volume.

Since the molecules do have attractive forces and volume (however small), van der Waals introduced into the theory two further constants to take these properties into account. Initially these constants had to be specific to each gas since the size of the molecules and the attractive force between them is different for each gas. Further work by van der Waals yielded the law of corresponding states – an equation that is the same for all substances. His valuable results enabled James Dewar and Heike Kamerlingh-Onnes to work out methods of liquefying the permanent gases.

In 1910 van der Waals was awarded the Nobel Prize for physics for his work on the equation of state. The weak electrostatic attractive forces between molecules and between atoms are called van der Waals forces in his honor.