François-Marie Raoult

Infobox Scientist
name = François-Marie Raoult
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birth_date = May 10, 1830
birth_place = Fournes
death_date = April 1, 1901
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nationality = French
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field = Chemistry
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known_for = Colligative properties
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François-Marie Raoult (May 10, 1830 - April 1, 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" of Nord. He became aspirant "répétiteur" at the Lycée of Reims in 1853, and after holding several intermediate positions was appointed in 1862 to the professorship of chemistry in Sens lycée. There he prepared a thesis on electromotive force which gained him a doctor's degree in Paris the following year.

In 1867 Raoult was put in charge of chemistry classes at Grenoble, 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 solutions, 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 solvents, such as benzene and acetic acid, in addition to water, led him to believe in a simple relation between the molecular weights of a solute and the freezing-point of a solution. He expressed the relationship as the "loi générale de la congélation", that if one molecule 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, 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, 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 Professor van 't Hoff in a memorial lecture delivered before the London Chemical Society on the 26th of March 1902. [cite journal | title = Raoult Memorial Lecture | author = Jacobus Henricus van 't Hoff | journal = J. Chem. Soc., Trans. | volume = 81 | issue = | pages = 969–981 | year = 1902 | url = | doi = 10.1039/CT9028100969 ]

Activities and honors

* Prix International de Chimie LaCaze (1889)
* Davy Medal (1892)
* Prix de l'Institut (1895)
* Commandeur de la Légion d'Honneur (1900)

See also

* Raoult's law

References

Further reading

*cite journal
title = Francois Marie Raoult (To 175th Anniversary of His Birthday)
author = Morachevskii, A. G.
journal = Russian Journal of Applied Chemistry
volume = 78
issue = 5
pages = 856–858
year = 2005
doi = 10.1007/s11167-005-0409-6

*cite journal
title = François-Marie Raoult: Past and Modern Look
author = Wisniak, Jaime
journal = The Chemical Educator
volume = 6
issue = 1
pages = 41–49
year = 2001
doi = 10.1007/s00897000432a

* cite journal | title = Francois-Marie Raoult, Master Cryoscopist | author = Getman, Frederick H.
journal = Journal of Chemical Education | volume = 13 | issue = | pages = 153–155 | year = 1936

External links

* (Contains reprints of three papers by Raoult)

* [http://web.lemoyne.edu/~giunta/raoult.html General Law of the Freezing of Solutions (Comptes Rendus 95, 1030 - 1033, 1882)]

* [http://web.lemoyne.edu/~giunta/raoult2.html General Law of the Vapor Pressure of Solvents (Comptes Rendus 104, 1430 - 1433, 1887)]

* [http://www.chemsoc.org/chembytes/ezine/2001/sutton_jul01.htm Brief Raoult biography] by Michael Sutton, Royal Society of Chemistry, 2001

*1911