van der Waals, Johannes Diderik

van der Waals, Johannes Diderik

(yōhä`nəs dē`dərĭk vän dər väls), 1837–1923, Dutch physicist. It had been known for some time that the behavior of real gases differs from that of an ideal gas as predicted by thermodynamicsthermodynamics,
branch of science concerned with the nature of heat and its conversion to mechanical, electric, and chemical energy. Historically, it grew out of efforts to construct more efficient heat engines—devices for extracting useful work from expanding hot gases.
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 and the kinetic-molecular theory of gaseskinetic-molecular theory of gases,
physical theory that explains the behavior of gases on the basis of the following assumptions: (1) Any gas is composed of a very large number of very tiny particles called molecules; (2) The molecules are very far apart compared to their sizes,
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. Van der Waals was led to the hypothesis of the continuity of the gaseous and liquid states of matter by combining the kinetic theory of gases with Laplace's theory of capillarity. In his theory of corresponding states (1880) he presented an equation of state (now named for him) for homogeneous substances in terms of pressure, volume, and temperature (see gas lawsgas laws,
physical laws describing the behavior of a gas under various conditions of pressure, volume, and temperature. Experimental results indicate that all real gases behave in approximately the same manner, having their volume reduced by about the same proportion of the
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); unlike the ideal gas law, his equation contains constant factors (different for each real substance) to account for the fact that molecules are of finite size and experience weak forces of mutual attraction (now called van der Waals forces). For that work and for discovering the law of binary mixtures he received the 1910 Nobel Prize in Physics. He was professor (1877–1907) at the Univ. of Amsterdam.
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