was a great French chemist who is often called the father of modern chemistry. Lavoisier was a scientist and thinker of unusually wide interests. He made contributions to many scientific fields. Lavoisier's brilliant scientific career was cut short by radicals of the French Revolution who had him executed by the guillotine in 1794. Lavoisiers most important contribution to science was his explanation of the chemical basis of combustion (fire). He observed that when the chemical elements sulfur and phosphorus are burned, they increase in weight. Lavoisier correctly assumed that these elements had combined chemically with air during combustion. Lavoisier did not know at that time, however, exactly what elements make up air. Then in 1774, Joseph Priestley of England discovered oxygen. (Priestley used a different name for the element; it is Lavoisier who coined the name "oxygen" Lavoisier realized that this element-oxygen-combines with substances when they burn.
Lavoisier's theories led to the rejection of the phlogistic doctrine, which had been accepted as a basic principle of chemistry for many years. This doctrine claimed that all flammable materials (materials that will burn) contain a substance called phlogiston. (The phl letter-group in phlogiston is pronounced like fl) When a substance burns, it gives up its phlogiston to the air, according to the theory. When Priestley discovered oxygen, for instance, he believed he had discovered dephlogisticated air He knew that substances burn in the presence of oxygen. He therefore assumed that oxygen readily absorbs the phlogiston given oft by the burning substances. This must mean that oxygen normally contains no phlogiston; therefore, it is "dephlogisticated."
Lavoisier, however, understood that oxygen combines with substances during combustion. By weighing the matter before and after combustion, he was able to confirm this idea. Lavoisier's discovery was one of the most important in the history of chemistry. It led to another important discovery-that matter cannot be created or destroyed, only changed in form. This important principle is known as the law of conservation of matter. Lavoisier developed a method for describing mathematically the chemical changes that matter can undergo. This method is the chemical equation. In a chemical equation, the mass of matter on the left side of the equation (before a chemical change) must equal the mass on the right side (after a chemical change). All chemists since Lavoisier's time have used the chemical equation in their work. Lavoisier also helped develop the system of chemical names now used. Lavoisier also made the fundamental discovery that water is made of hydrogen and oxygen. Unknown to him, the English chemist Henry Cavendish had discovered this fact a short time earlier. Lavoisier studied respiration in animals as a chemical process. He came to the conclusion that respiration is a kind of combustion. In respiration, oxygen is chemically combined wit) nutrients such as simple sugars. In this chemical reaction, heat is given off. Heat is a form of energy an organism must use to stay alive. Also, waste products such as carbon dioxide are given off. In describing respiration chemically, Lavoisier laid the foundation for modern biochemistry Lavoisier published his doctrines of chemistry in the Elementary Treatise on Chemistry in 1789. This became one of the most important early textbooks on chemistry. It also enabled other chemists to learn about Lavoisie ideas. Lavoisier was involved in public service for much of his adult life. This career gave Lavoisier many opportunities to apply his mathematical and scientific talents to practical use. As a young man, he joined the geologist J. Guettard in a geological survey trip through out France. Afterward, Lavoisier helped Guettard prepare a mineralogical atlas of France. He helped improve the manufacture of gunpowder. In agriculture, he established a model farm where principles of scientific agriculture were demonstrated. Also, Lavoisier served on the commission that devised the metric system, a uniform and scientific system of measurements. The French government adopted the metric system in 1795. Today it is used in most countries of the world and is the system of measurement used in science. Antoine Lavoisier was born in 1743 of a well- to-do family in Paris. He received an excellent education. In 1766 young Lavoisier won gold medal from the French Academy of Sciences for a plan of lighting city streets. Two years later he became a member of the Academy. Lavoisier received a title of nobility in 1772. He also served in the French civil service, notably as a member of the nation's tax-collecting body. For these reasons, Lavoisier became the target of radical politicians who seized power in the early 1790's during the French Revolution. In 1792 Lavoisier was forced to leave hi.' house and laboratory. In May, 1 794, he was ~ rested and forced to stand trial. The revolutionaries made no effort to give Lavoisier a trial. He was convicted and condemned to death. Lavoisier was beheaded by the guillotine on May 8,1794.
No comments:
Post a Comment