Johannes van der Waals
Johannes Diderik van der Waals
November 23 1837
|Died||March 8 1923 (aged 85)
|Institutions||University of Amsterdam|
|Alma mater||University of Leiden|
|Academic advisor||Pieter Rijke|
|Notable students||Diederik Korteweg|
|Known for||van der Waals equation of state|
|Notable prizes||Nobel Prize for Physics (1910)|
|He is notably the father of the poet Jacqueline Elisabeth and the physicist Johannes Diderik Jr.|
Johannes Diderik van der Waals (November 23, 1837 – March 8, 1923) was an outstanding Dutch physicist who was the first to obtain an equation of state that describes the condition of both gases and liquids in terms of their pressure, temperature, and volume. His equation is more general than the so-called "ideal gas law" in that it takes into consideration the effect of intermolecular forces and the sizes of molecules, both of which are assumed to be negligible in an ideal gas.
Johannes Diderik van der Waals was born in the Dutch city of Leiden. He was the eldest of eight children of Jacobus van der Waals, a carpenter, and his wife, Elisabeth van den Burg. Because of the family's financial circumstances, van der Waals was unable to attend a formal secondary school that taught Latin and Greek, but he did complete an extended elementary school education. He was able to obtain teaching licenses by studying on his own and passing standard tests.
Van der Waals taught primary school from 1856 to 1861, and from 1862 to 1865 he studied mathematics and physics at the University of Leiden. In 1864, he obtained a position at a high school in Deventer, teaching mathematics and physics. The following year, he was married to Anna Magdalena Smit. The couple had three daughters and a son: Anne Madeleine; Jacqueline Elisabeth, who became a poet; Johanna Diderica; and Johannes Diderik Jr., who followed his father's footsteps and became a physicist.
In 1866, van der Waals moved to the Hague, where he taught at a high school, eventually becoming its headmaster. He continued to study advanced mathematics and physics at the University of Leiden, but because of his lack of a formal secondary school education, had to obtain an exemption in order to proceed with a doctoral program. The state eventually dropped the classical language requirements. Studying under Pieter Rijke, he was awarded a doctorate in 1873 based on a dissertation that quickly caught the attention of the international scientific community.
Van der Waals's thesis was entitled Over de Continuïteit van den Gas- en Vloeistoftoestand (On the continuity of the gas and liquid state). In this thesis he derived the equation of state bearing his name. The importance of this work is that it gave a model in which the liquid and the gas phase of a substance merge into each other in a continuous manner. It shows that the two phases are in fact of the same nature. In deriving his equation of state van der Waals assumed not only the existence of molecules (which in physics was disputed at the time), but also that they are of finite size and attract each other. Since he was one of the first to postulate an intermolecular force, however rudimentary, such a force is now sometimes called a van der Waals force.
For an ideal gas—one in which the size and mutual attraction of the molecules can be neglected—the product of the pressure and the volume of a sample of gas is proportional to the absolute temperature. Van der Waals added terms to both the pressure and the volume to account for the mutual attraction of molecules and to their size, respectively. His equation includes two constants that are different for different gases.
One of the conclusions that could be drawn from van der Waals's research was that there exists a critical temperature for a gas above which it is impossible to condense the gas into a liquid.
Van der Waals found the inspiration for his thesis after reading the 1857 treatise by Rudolf Clausius entitled Über die Art der Bewegung welche wir Wärme nennen (On the Kind of Motion which we Call Heat), along with other papers and books by Clausius. Van der Waals was later greatly influenced by the writings of James Maxwell, Ludwig Boltzmann, and Josiah Willard Gibbs, who were all working on similar problems in the kinetic theory of gases.
It did not take long for the scientific community to latch onto the new results. Maxwell, who had already developed his own theory on the motion of molecules in a gas, praised van der Waals for his work. "This at once puts his name among the foremost in science," Maxwell said in Nature magazine a year after van der Waals's dissertation was published.
Based on his equation of state, van der Waals was able to estimate the size of a hydrogen molecule.
Accolades quickly followed. In 1875, he was admitted as a member to the Royal Academy of Arts and Sciences, and in 1877, he was appointed professor of physics at the University of Amsterdam.
A second great discovery of van der Waals was published in 1880: The Law of Corresponding States. This law shows that after scaling temperature, pressure, and volume by their respective critical values, a general form of the equation of state is obtained which is applicable to all substances. This law served as a guide during the experiments that led to the liquefaction of helium by Heike Kamerlingh Onnes. A decade later van der Waals was able to address the situation of a material composed of a mixture of two substances.
In 1881, van der Waals installed new laboratory facilities in Amsterdam. Although he was keenly interested in the experimental side of physics, it is said that he did not conduct experiments himself, but generally used the services of an assistant. Throughout the 1880s, he was in close communication with Kamerlingh Onnes, who was conducting experiments on the liquefication and solidification of gases at very low temperatures.
Van der Waals remained active with the Royal Society throughout his career, and served as its secretary from 1896 to 1912. In 1898, he had all papers submitted to the society translated into english so that they could reach a wider audience.
He retired from the University of Amsterdam in 1908.
For his work on the behavior of liquids and gases, he won the 1910 Nobel Prize in physics.
Van der Waals died in Amsterdam in 1923.
Van der Waals joins a long list of scientists who were high school teachers when they made major contributions to their fields. In spite of his lack of formal schooling, Van der Waals showed persistence in the face of adversity, and didn't complete his doctorate until he was in his 30s. He is certainly a model for those who have not taken the ordinary road of higher education.
Van der Waals's life testifies to the importance of teaching in the advancement of the sciences. A teacher must explain concepts and experiments clearly to his or her students, and this leads to the necessity of clarifying the various ideas that amake up the body of scientific knowledge. This kind of scrutiny is a fertile field for discovery, as has been proven over and over again in the lives of many scientists, from John Dalton to Josef Loschmidt, to van der Waals himself.
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