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 (, ) is one of the three levels of government under the national level (" territorial collectivities"), between the administrative regions and the communes. There are a total of 101 ...
'' 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 14.
* ''Lycées'' () provide a three-year course of further secondary education for students between ...
of
Reims
Reims ( ; ; also spelled Rheims in English) is the most populous city in the French Departments of France, department of Marne (department), Marne, and the List of communes in France with over 20,000 inhabitants, 12th most populous city in Fran ...
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 physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...
in
Sens
Sens () is a Communes of France, commune in the Yonne Departments of France, department in Bourgogne-Franche-Comté in north-central France, 120 km southeast from Paris.
Sens is a Subprefectures in France, sub-prefecture and the second la ...
lycée. There he prepared a thesis on
electromotive force
In electromagnetism and electronics, electromotive force (also electromotance, abbreviated emf, denoted \mathcal) is an energy transfer to an electric circuit per unit of electric charge, measured in volts. Devices called electrical ''transducer ...
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
Grenoble ( ; ; or ; or ) is the Prefectures in France, prefecture and List of communes in France with over 20,000 inhabitants, largest city of the Isère Departments of France, department in the Auvergne-Rhône-Alpes Regions of France, region ...
, 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
A galvanic cell or voltaic cell, named after the scientists Luigi Galvani and Alessandro Volta, respectively, is an electrochemical cell in which an electric current is generated from spontaneous oxidation–reduction reactions. An example of a g ...
; 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
* Solu ...
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 (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...
s, such as
benzene
Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal Ring (chemistry), ring with one hyd ...
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 compone ...
, 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 that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...
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 that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...
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 equilibrium vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indicat ...
, 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
Jacobus Henricus van 't Hoff Jr. (; 30 August 1852 – 1 March 1911) was a Dutch physical chemist. A highly influential theoretical chemist of his time, Van 't Hoff was the first winner of the Nobel Prize in Chemistry. His pioneering work ...
and
Wilhelm Ostwald
Wilhelm Friedrich Ostwald (; – 4 April 1932) was a Latvian 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 Arrhenius. ...
, 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
Ernst Otto Beckmann (July 4, 1853 – July 12, 1923) was a German pharmacist and chemist who is remembered for his invention of the Beckmann differential thermometer and for his discovery of the Beckmann rearrangement.
Scientific work
Ernst Ot ...
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 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). Re ...
(1892)
* Prix de l'Institut (1895)
* Commandeur de la
Légion d'Honneur
The National Order of the Legion of Honour ( ), formerly the Imperial Order of the Legion of Honour (), is the highest and most prestigious French national order of merit, both military and Civil society, civil. Currently consisting of five cl ...
(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
Commanders of the Legion of Honour