Van't Hoff, Jacobus Henricus (1852-1911) was a Dutch chemist who received the first Nobel Prize in chemistry in 1901. His work led to the development of stereochemistry, which deals with the three-dimensional arrangements of atoms in the structure of molecules.
Van't Hoff was born in 1852 in Rotterdam, the Netherlands. In 1871, he earned a technical diploma at the Polytechnic School in Delft, completing a three-year chemistry program in two years. He then entered the University of Leiden, where he studied mainly mathematics. He continued his studies in Germany and Paris and earned his doctorate in chemistry at the University of Utrecht, the Netherlands, in 1874.
In 1876, van't Hoff became a lecturer in physics at the State Veterinary School at Utrecht. In 1877, he went to the University of Amsterdam as lecturer in chemistry. He became a professor the next year and later became chairman of the chemistry department.
While working on his doctorate in 1874, van't Hoff also published Proposal for the Extension of the Formulas Now in Use in Chemistry into Space, which described his research in stereochemistry. In the mid-1800's, French chemist Louis Pasteur had worked with isomers —two or more chemical compounds having the same molecular formula but differing in some of their properties. Pasteur had discovered that when isomers are crystallized, they differ optically. One compound rotates a beam of polarized light to the left, and the other rotates it to the right. He believed the structures of the compounds were asymmetrical but was unable to explain how. Van't Hoff theorized that the optical isomers differed in their molecular arrangement. He stated that the four chemical bonds of carbon atoms, represented as four directions lying in the same plane, actually are directed to the corners of a tetrahedron. Such three-dimensional carbon atoms can exist in only two forms, which are mirror images of each other, and the opposite tetrahedral arrangements explain the oppositional optical rotation. Van't Hoff's theory met at first with considerable criticism from the scientific community, but eventually it gained wide acceptance. French chemist Joseph Achille Le Bel independently arrived at the same conclusion at about the same time, but in a more abstract form.
Van't Hoff also studied double- and triple-linked carbon atoms. A double-linked compound consists of two tetrahedrons with one edge in common, as in certain acids. He also proposed that the effects of circularly polarized light in the atmosphere cause optically inactive substances to become optically active. In 1893, he and Le Bel were awarded the Davy Medal of the Royal Society of London for their work in stereochemistry.
In the early 1880's, van't Hoff shifted his focus to physical chemistry and thermodynamics, detailing his findings in Studies in Dynamic Kinetics (1884). In experiments that attempted to explain certain oxidation processes, he discovered the law of mobile equilibrium, which showed that the internal temperature equilibrium of a system shifts to oppose the external temperature around it. In other words, a lower external temperature will cause heat development, and an increase in external temperature results in heat absorption.
Subsequent research included studies on the effect of osmotic pressure on gases and dilute solutions. Van't Hoff conducted experiments on the effect of a salt solution on pure water and determined values by methods such as altering vapor pressure and temperature. In 1886, he demonstrated that solute particles in a dilute solution behave much the same as particles of a gas and occupy a volume equal to the solvent. This proved that thermodynamic laws pertained to both gases and dilute solutions. These osmotic pressure laws also apply to electrolytic dissociation.
In 1896, van't Hoff was elected to the Royal Prussian Academy of Sciences and became a professor there as well as at the University of Berlin. He held both posts until his death in 1911. He studied solid solutions and double salts, and in 1897 published his findings on the formation, separation, and conversion of many double salts, such as tartrates of sodium, ammonium, and potassium. He also examined the origins of oceanic deposits and the conditions of oceanic salt deposits, particularly those formed at Stass-furt. This was possibly the first time small-scale laboratory results were applied to large-scale natural phenomena. The results of the study of oceanic salts were especially valuable to the German potash industry.
Van't Hoff received the Helmholtz Medal of the Prussian Academy of Sciences in 1911.