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François-Marie Raoult (; 10 May 1830 – 1 April 1901) was a French chemist who conducted research into the behavior of solutions, especially their physical properties.


Life and work

Raoult was born at Fournes, in the ''
département In the administrative divisions of France, the department (french: département, ) is one of the three levels of government under the national level (" territorial collectivities"), between the administrative regions and the communes. Ninety ...
'' of
Nord Nord, a word meaning "north" in several European languages, may refer to: Acronyms * National Organization for Rare Disorders, an American nonprofit organization * New Orleans Recreation Department, New Orleans, Louisiana, US Film and televisi ...
. He became aspirant ''répétiteur'' at the
Lycée In France, secondary education is in two stages: * ''Collèges'' () cater for the first four years of secondary education from the ages of 11 to 15. * ''Lycées'' () provide a three-year course of further secondary education for children between ...
of
Reims Reims ( , , ; also spelled Rheims in English) is the most populous city in the French department of Marne, and the 12th most populous city in France. The city lies northeast of Paris on the Vesle river, a tributary of the Aisne. Founded b ...
in 1853, and after holding several intermediate positions was appointed in 1862 to the professorship of
chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...
in
Sens Sens () is a commune in the Yonne department in Bourgogne-Franche-Comté in north-central France, 120 km from Paris. Sens is a sub-prefecture and the second city of the department, the sixth in the region. It is crossed by the Yonne an ...
lycée. There he prepared a thesis on
electromotive force In electromagnetism and electronics, electromotive force (also electromotance, abbreviated emf, denoted \mathcal or ) is an energy transfer to an electric circuit per unit of electric charge, measured in volts. Devices called electrical '' tran ...
which gained him a doctor's degree in Paris the following year. In 1867 Raoult was put in charge of chemistry classes at the University of
Grenoble lat, Gratianopolis , commune status = Prefecture and commune , image = Panorama grenoble.png , image size = , caption = From upper left: Panorama of the city, Grenoble’s cable cars, place Saint- ...
, and three years later he succeeded to the chair of chemistry, which he held until his death in 1901. Raoult's earliest researches were physical in character, being largely concerned with the phenomena of the voltaic cell; later there was a period when more purely chemical questions engaged his attention. Raoult's name is best known in connection with work on
solution Solution may refer to: * Solution (chemistry), a mixture where one substance is dissolved in another * Solution (equation), in mathematics ** Numerical solution, in numerical analysis, approximate solutions within specified error bounds * Solutio ...
s, to which he devoted the last two decades of his life. His first paper describing how solutes depressed the freezing points of solutions was published in 1878. Further experiments with various
solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
s, such as
benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...
and
acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main componen ...
, in addition to water, led him to believe in a simple relation between the
molecular weight A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bio ...
s of a solute and the freezing-point of a solution. He expressed the relationship as the ''loi générale de la congélation'' (general law of freezing), that if one
molecule A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and b ...
of a substance be dissolved in 100 molecules of any given solvent, the temperature of solidification of the latter will be lowered by 0.63 °C. Another relation on which Raoult worked was that concerning the depression of a solvent's
vapor pressure Vapor pressure (or vapour pressure in English-speaking countries other than the US; see spelling differences) or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed pha ...
, due to a solute, showing that the decrease is proportional to the solute's molecular weight. This relationships holds best in the limiting case of a dilute solution. These two generalizations afforded a new method of determining the molecular weights of dissolved substances, and were utilized by Jacobus van 't Hoff and
Wilhelm Ostwald Friedrich Wilhelm Ostwald (; 4 April 1932) was a Baltic German chemist and philosopher. Ostwald is credited with being one of the founders of the field of physical chemistry, with Jacobus Henricus van 't Hoff, Walther Nernst, and Svante Arrhen ...
, among other chemists, in support of the hypothesis of electrolytic dissociation in solutions. Raoult's freezing-point depression method became even more useful after it was improved by Ernst Otto Beckmann and became a standard technique for determining molecular weights of organic substances. An account of Raoult's life and work was given by van 't Hoff in a memorial lecture delivered before the
London Chemical Society London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has been a major se ...
on 26 March 1902.


Activities and honors

* Prix International de Chimie LaCaze (1889) *
Davy Medal The Davy Medal is awarded by the Royal Society of London "for an outstandingly important recent discovery in any branch of chemistry". Named after Humphry Davy, the medal is awarded with a monetary gift, initially of £1000 (currently £2000). H ...
(1892) * Prix de l'Institut (1895) * Commandeur de la Légion d'Honneur (1900)


References


Further reading

* * *


External links

* * (Contains reprints of three papers by Raoult)
General Law of the Freezing of Solutions (Comptes Rendus 95, 1030 - 1033, 1882)


* {{DEFAULTSORT:Raoult, Francois Marie 19th-century French chemists Members of the French Academy of Sciences 1830 births 1901 deaths