Pierre Louis Dulong

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Pierre Louis Dulong

Pierre Louis Dulong (born February 12, 1785 in Rouen , † July 19, 1838 in Paris ) was a French medic, physicist and chemist .

Life

As an only child, he lost both parents at the age of 4. As a well-to-do orphan he was taken in by his aunt in Auxerre . He attended high school in Auxerre and then the Lycée Corneille in Rouen before he passed the entrance exam at the École polytechnique in Paris in 1801 . Initially, he wanted to study marine engineering there, but then went to the artillery school for lack of a place to study. However, health problems forced him to leave the artillery school before the end of the second year. PL Dulong then studied physics and chemistry at the École polytechnique in Paris .

He began studying human medicine , studied and worked as a doctor for some time in a poor district in Paris, the Faubourg Saint-Marceau . He then turned to the natural sciences, such as botany, and worked in the chemistry laboratory of Claude-Louis Berthollet (1748–1822), where he a. a. works on the solubility of salts. PL Dulong also got to know the enormous explosiveness of nitrogen trichloride (NCl 3 ), in 1812 he lost two fingers and one eye in one of his experiments. In 1820 he was appointed professor at the École Polytechnique and in 1830 director of studies .

From 1823 he was a member of the Académie des Sciences and in 1832 became its permanent secretary. From July 1807 he was mentioned in the Mémoires de Physique et de Chimie de la Société d'Arcueil as a member of the Société d'Arcueil . In 1826 he became a Fellow of the Royal Society of London and in 1836 an Honorary Fellow of the Royal Society of Edinburgh . In 1827 he was elected a corresponding member of the Prussian Academy of Sciences . His name is immortalized on the Eiffel Tower, see: The 72 names on the Eiffel Tower .

Pierre Louis Dulong died in Paris on July 19, 1838.

Burial place of Pierre Louis Dulong in the Parisian cemetery Le Cimetière du Père-Lachaise

Scientific achievements

PLDulong is best known for the Dulong-Petit rule , which is also named after him , that the specific heat capacity of solids, e.g. B. Metals linked with their molar mass . That this is a rule can be seen from the fact that there are deviations, especially for elements with a lower atomic mass and at lower temperatures. He made this discovery together with Alexis Thérèse Petit (1791-1820). Both discovered the law of the constancy of atomic heat in 1818/1819 (see also Chemistry in Modern Times ).

The product of the specific heat and atomic mass of solid elements is almost constant and averages 6.2 cal:

Atomic mass • specific heat = atomic heat ≈ 6.2 cal (25.9408 joules)

From this connection, the approximate atomic mass of solids can be determined on the basis of the estimate atomic mass ≈ 6.2 / spec. Warmth. The determination is not very exact since the value 6.2 is only an average value.

Contemporary theories explain this connection as follows: The possibilities of movement of the atoms of a solid body are limited and occur in elastic oscillations around certain centers of gravity in the crystal lattice. Formally there are only three degrees of freedom or possibilities of movement in a three-dimensional space. From an energetic point of view, however, every degree of freedom counts twice, since not only kinetic energy (when the atoms vibrate), but also potential energy is stored. To heat a defined amount of a solid body by 1 ° C at constant volume, the amount of heat C v (or atomic heat at constant volume) is:

3R ≈ 5.96 cal per mole of the element required (see also the thermal equation of state of ideal gases ). Here R is the universal gas constant .

He also worked on the structure of nitrogen trichloride (1811), where he lost an eye and two fingers due to the explosions of this dangerous compound . He also succeeded in synthesizing phosphinic acid (1816).

In 1815, almost simultaneously with Humphry Davy (1778–1829), he proposed the hydrogen theory of acids (see also acid-base concepts ).

Works

  • Dulong, PL: Recherches sur la décomposition mutuelle des sels insolubles et des sels solubles . Annales de Chimie, t. LXXXII
  • Dulong, PL: Mémoire sur une nouvelle matière détonante (Mémoires de la Société d'Arcueil, t. III);
  • Dulong, PL: Recherches sur les lois de la dilatation des solides, des liquides et des fluides élastiques, et sur la mesure exacte des températures . Annales de Chimie et de Physique, t. II
  • Dulong, PL: Observations sur quelques combinaisons de l'azote et de l'oxygène (ibid.);
  • Dulong, PL: Mémoire sur les combinaisons du phosphore avec l'oxygène (Mémoires de la Société d'Arcueil, t. III);
  • Dulong, PL: Recherches sur la mesure des températures et sur les lois de la communication de la chaleur . Annales de Chimie et de Physique, t. VIl
  • Dulong, PL: Recherches sur quelques points importants de la théorie de la chaleur . (ibid., t. X);
  • Dulong, PL: Nouvelle détermination des proportions de l'eau et de la densité de quelques fluides élastiques . (ibid., t. XV);
  • Dulong, PL: Notes sur la propriété que possèdent quelques métaux de faciliter la combinaison des fluides élastiques . (Mémoires de l'Institut, t. V);
  • Dulong, PL: Recherches sur les pouvoirs réfringents des fluides élastiques (ibid., T. X);
  • Dulong, PL: Recherches sur la force élastique de la vapeur d'eau (ibid., T. X);
  • Dulong, PL: Rapport, fait le 9 janvier 1832, avec MM. Arago, Prony et Cordier, sur un Mémoire relatif aux appareils producteurs de la vapeur, lu à l'Académie des Sciences, par le baron Seguier; Paris, 1832, in-8 °

literature

Web links

Individual evidence

  1. ^ Lycée Pierre Corneille de Rouen: The Lycée Corneille of Rouen
  2. ↑ Ken Okada, Miyako Akiyoshi, Keiko Ishizaki, Hiroyasu Sato, Takehiro Matsunaga: Analysis of an explosion accident of nitrogen trichloride in a waste liquid containing ammonium ion and platinum black. In: Journal of Hazardous Materials. 278, 2014, pp. 75-81, doi: 10.1016 / j.jhazmat.2014.05.077 .
  3. ↑ entry on Dulong; Pierre Louis (1785-1838) in the Archives of the Royal Society , London
  4. ^ Fellows Directory. Biographical Index: Former RSE Fellows 1783–2002. (PDF) Royal Society of Edinburgh, accessed October 22, 2019 .
  5. ^ Members of the previous academies. Pierre Louis Dulong. Berlin-Brandenburg Academy of Sciences , accessed on March 17, 2015 .
personal data
SURNAME Dulong, Pierre Louis
BRIEF DESCRIPTION French physicist and chemist
DATE OF BIRTH February 12, 1785
PLACE OF BIRTH Rouen
DATE OF DEATH July 19, 1838
Place of death Paris , France