Sabtu, 17 Februari 2018

ANTOINE LAURENT LAVOISIER

ANTOINE LAVOISIER


Antoine-Laurent de Lavoisier was a French nobleman and chemist who was central to the 18th-century chemical revolution and who had a large influence on both the history of chemistry and the history of biology. He is widely considered in popular literature as the "father of modern chemistry".

Lavoisier was a powerful member of a number of aristoctatic councils, and an administrator of the Ferme generale. The Ferme générale was one of the most hated components of the Ancien Regime because of the profits it took at the expense of the state, the secrecy of the terms of its contracts, and the violence of its armed agents. All of these political and economic activities enabled him to fund his scientific research. At the height of the French Revolution, he was charged with tax fraud and selling adulterated tobacco, and was guilotined.


Early life and education


Antoine-Laurent Lavoisier was born to a wealthy family of the nobility in Paris on 26 August 1743. The son of an attorney at the Parliament of Paris, he inherited a large fortune at the age of five upon the death of his mother. Lavoisier began his schooling at the College des Quatre-Nations, University of Paris in Paris in 1754 at the age of 11. In his last two years (1760–1761) at the school, his scientific interests were aroused, and he studied chemistry, botany, astronomy, and mathematics. In the philosophy class he came under the tutelage of Abbe Nicolas Louis de Lacaille, a distinguished mathematician and observational astronomer who imbued the young Lavoisier with an interest in meteorological observation, an enthusiasm which never left him. Lavoisier entered the school of law, where he received a bachelor's degree in 1763 and a licentiate in 1764. Lavoisier received a law degree and was admitted to the bar, but never practiced as a lawyer. However, he continued his scientific education in his spare time.

Early scientific work

Lavoisier's education was filled with the ideals of the French Enlightenment of the time, and he was fascinated by Pierre Maquer's dictionary of chemistry. He attended lectures in the natural sciences. Lavoisier's devotion and passion for chemistry were largely influenced by Etienne Condillac, a prominent French scholar of the 18th century. His first chemical publication appeared in 1764. From 1763 to 1767, he studied geology under Jean-Etienne Guettard. In collaboration with Guettard, Lavoisier worked on a geological survey of Alsace-Lorraine in June 1767. In 1764 he read his first paper to the French Academy of Sciences, France's most elite scientific society, on the chemical and physical properties of gypsum (hydrated calsium sulfate), and in 1766 he was awarded a gold medal by the King for an essay on the problems of urban street lighting. In 1768 Lavoisier received a provisional appointment to the Academy of Sciences. In 1769, he worked on the first geological map of France.

Contributions to chemistry

Oxygen Theory of Combustion

During late 1772 Lavoisier turned his attention to the phenomenon of combustion, the topic on which he was to make his most significant contribution to science. He reported the results of his first experiments on combustion in a note to the Academy on 20 October, in which he reported that when phosphorus burned, it combined with a large quantity of air to produce acid spirit of phosphorus, and that the phosphorus increased in weight on burning. In a second sealed note deposited with the Academy a few weeks later (1 November) Lavoisier extended his observations and conclusions to the burning of sulfur and went on to add that "what is observed in the combustion of sulfur and phosphorus may well take place in the case of all substances that gain in weight by combustion and calcination: and I am persuaded that the increase in weight of metallic calces is due to the same cause, oxygen"
Metal combustion scheme with oxygen

Pioneer of stoichiometry

Lavoisier's researches included some of the first truly quantitative chemical experiments. He carefully weighed the reactants and products of a chemical reaction in a sealed glass vessel so that no gases could escape, which was a crucial step in the advancement of chemistry.[36] In 1774, he showed that, although matter can change its state in a chemical reaction, the total mass of matter is the same at the end as at the beginning of every chemical change. Thus, for instance, if a piece of wood is burned to ashes, the total mass remains unchanged if gaseous reactants and products are included. Lavoisier's experiments supported the law of conservation of mass.


Legacy


Compsition and Chemical Change
Lavoisier also did early research in physical chemistry and thermodynamics in joint experiments with Laplace. They used a calorimeter to estimate the heat evolved per unit of carbon dioxide produced, eventually finding the same ratio for a flame and animals, indicating that animals produced energy by a type of combustion reaction.
Lavoisier's Laboratory, Musee des Arts et Metiers, Paris.

Statue of Lavoisier, at Hotel de Ville, Paris
He was essentially a theorist, and his great merit lay in his capacity to take over experimental work that others had carried out—without always adequately recognizing their claims—and by a rigorous logical procedure, reinforced by his own quantitative experiments, expounding the true explanation of the results. He completed the work of Black, Priestley and Cavendish, and gave a correct explanation of their experiments.

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