Chapter 94 Lavoisier

The chemical revolution carried out by the French chemist Lavoisier is widely regarded as one of the most brilliant achievements in the history of scientific development in the 18th century.In this revolution, based on eloquent experimental facts, he overthrew the theory of phlogiston that had dominated chemical theory for a hundred years, and established a combustion theory centered on oxygen.In response to the chaotic situation in the naming of chemical substances at that time, Lavoisier worked with others to formulate the principles of naming chemical substances and created a new system of chemical substance classification.Based on the experience of chemical experiments, Lavoisier explained the law of conservation of mass and its application in chemistry in clear language.These works, especially the new ideas, new theories, and new ideas he put forward, laid an important foundation for the development of modern chemistry.

Lavoisier originally studied law. In 1763, at the age of 20, Lavoisier obtained a bachelor's degree in law and obtained a lawyer's license.Lavoisier's father was a well-known lawyer with a wealthy family, so Lavoisier did not immediately become a lawyer.At that time, he became interested in botany, and he often went up to the mountains to collect specimens, which made him interested in meteorology again.At the suggestion of the geologist Gottard, Lavoisier studied chemistry with the famous Paris professor Iller.Since then, Lavoisier has had an indissoluble bond with chemistry. Lavoisier is the founder of modern chemistry.His main achievement is to synthesize many experimental results in the past and at that time, making it a complete theory.

In 1766, at the age of 23, Lavoisier won the gold medal of the French Academy of Sciences for his thesis "On the Problem of Urban Lighting". In 1772, he was elected as a member of the French Academy of Sciences due to his fruitful research on natural water.His hundred-day-long experiment of "burning dry water will not turn soil" is well known.Through this experiment, he overturned the theory that matter cannot be transformed into each other, and further proved the correctness of matter's indestructibility. Lavoisier, who was skeptical of the "phlogiston" theory, could hardly accept the view that "phlogiston" was the cause of material combustion. In February 1772, he read a research report by Darcey, which mentioned that "diamonds burned hot at high temperatures will disappear without a trace", and this experimental result inspired him deeply.So what happens when you heat a diamond in the absence of air?So he covered the diamonds with a thick layer of graphite that had been made into a paste, and then put these black balls in a raging fire and burned them red.A few hours later, when the graphite coat was peeled off, the diamond inside was intact!Lavoisier wondered: "The disappearance of the diamond seems to be related to the air! Could it have interacted with the air?" This kind of thinking was completely opposite to the popular "phlogiston" theory at that time!

In order to prove his idea, he conducted a series of experiments with white phosphorus. Without exception, the white smoke produced after burning white phosphorus was heavier than white phosphorus, which proved that "phosphorus and air were combined."During the combustion process of white phosphorus, only 1/5 of the air can support the combustion. Lavoisier temporarily called this air "useful air". At this point, it should be said that the "phlogiston" theory can be overturned, but Lavoisier still refused to draw conclusions rashly. In 1774, he made a quantitative study by heating metal in a retort with a balance, and the result still proved his idea!

"If pure 'useful air' can be extracted from metal ash, then my combustion theory will be unassailable!" According to his new idea, in October 1774, after he heated mercury ash, he collected "Dephlogisticated air" really has the properties he predicted for "useful air".At this time, Lavoisier firmly believed: there is absolutely no "phlogiston", the combustion of combustible substances, or the transformation of metal into calcined ash is not a decomposition reaction, but a combination with "useful air"! In 1777, he officially named this "useful air" oxygen.

Lavoisier, who has always been serious and cautious, conducted a large number of combustion experiments in the five years from 1772 to 1777, studied the substances produced after combustion and the remaining gases one by one, and finally synthesized, summarized and analyzed the experimental results .It was not until 1777 that he formally submitted a research report to the French Academy of Sciences, entitled "Introduction to Combustion".This theory completely overthrew the "phlogiston" theory that was dominant at that time for a hundred years, completely cut off the connection between chemistry and alchemy, and made all the chemistry that had been reversed on the wrong basis of the "phlogiston" theory for 100 years reappear. The true colors of science have been restored, and the science of chemistry has taken a big step forward!

In the history of chemical development, the first reasonable nomenclature of chemical substances was jointly drawn up by Lavoisier and three other chemists.After that, the chemical reaction process and its quantitative relationship began to be explained with preliminary chemical reaction equations.Lavoisier completed the chemical revolution with the new chemical language established in 1787 and the "Basic Course of Chemistry" published in 1789, transforming chemical science in 17 years. Lavoisier has extraordinary scientific insight and courageous spirit.He worked hard all his life, getting up at 6 o'clock every day, conducting experimental research from 6 o'clock to 8 o'clock, working as the director of gunpowder or a member of the French Academy of Sciences from 8 o'clock to 7 o'clock in the afternoon, and concentrating on his scientific research from 7 o'clock to 10 o'clock in the evening.Don't rest on Sunday, do a full day of experimental work.