Lavoisier was dedicated to the experimental study of metal rusting and combustion. His experiments with phosphorus and sulfur convinced him that, instead of losing something when burned, the substances weighed more after being burned than before. Lavoisier invented very delicate scales that allowed him to do his job. He is admittedly one of the fathers of modern Chemistry as a result of experiments that demonstrated the important law of conservation of matter (or of the masses), which is stated as follows: "The sum of the masses of the reactive substances is equal to the sum of the masses of the reaction products."
This law is the cornerstone of modern chemical formulas, everything has to be the same in the end. Antoine Lavoisier performed another experiment, burned a diamond in pure oxygen and obtained carbon dioxide as a result.
This proved that the diamond and the coal at the bottom are chemically the same things: carbon. He carried out studies in Physiology and The biochemistry that established the methods of basal metabolism tests.
He carried out experiments on guinea pigs, rigorously measuring the oxygen they consumed and the released carbon dioxide.
It was the first to demonstrate that the heat of the human the body is produced by a process of "burning" that happens continuously in our body and that results from the combination of food and oxygen.
This explains that when chemicals react, they are not lost. That is, they transform into others, so that these elements remain, however, differently, as their atoms are rearranged. Chemical equations are a graphic way of observing this transformation, for example, in the formation of carbon dioxide: C + O → CO2 summary The Law of Conservation of Masses or Law of Conservation of Matter proposed by Lavoisier postulates that: "The sum of the masses of the reactive substances is equal to the sum of the masses of the reaction products." To reach these conclusions, Lavoisier used precise scales involving several elements in closed containers. The total masses of the elements did not vary before (reactants) and after the reaction (products), remaining constant. Note that if he performed his experiments in an open environment there would be a loss of mass since the substance would react with air. In this case, if we observe an iron that over time reacts with air (resulting in rust), we notice the variation in its initial mass. That is, it becomes larger after contact between them since it has the mass of iron and the mass of air. Thus, it is clear that Lavoisier's Law is only applied in closed systems.
Proust's law In addition to the Mass Conservation Law, the French scientist Joseph Louis Proust (1754-1826) formulated in 1801 the “Law of Constant Proportions”. These two laws mark the beginning of modern chemistry called "Weight Laws". Thus, scientists focused on studying the masses of substances involved in chemical reactions. In such a way, the Law of Constant Proportions postulates that: "A compound substance is made up of simpler substances that are always joined in the same mass ratio". As an example of this law, we can think 3g of carbon (C) that join with 8g of oxygen resulting in 11g of carbon dioxide (CO2) or; 6g of carbon (C) that join with 16g of oxygen, resulting in 22g of carbon dioxide.
Lavoisier repeated Henry Cavendish's experiments on fuel gas, the “flammable air”, which when burned appeared water, and explained the meaning.
Water is a compound of two gases, oxygen and hydrogen. For many scientists at the time, this was hard to believe. Lavoisier called the “flammable air” hydrogen.
Lavoisier had a strong interest in agriculture and owned a large farm in Le Bourget, where he demonstrated the importance of fertilizers and an adequate amount of pasture and crops. By applying scientific principles to agriculture, wheat production and the size of his herd doubled.
Nothing is created, nothing is lost and everything is transformed.