The discovery of molecules and atoms was a major event in the development of atomic-molecular theory. Back in 1748, the great Russian scientist Mikhail Vasilievich Lomonosov formulated the law of conservation of mass as a philosophical concept. Subsequently, he himself brought a powerful practical and theoretical base under her proof, and this happened in 1756. In parallel with a Russian scientist, a French chemist A.L. Lavoisier worked on this problem. He proposed his own version of the proof in 1789.
The law of conservation of mass of a substance states that the sum of the masses of all substances that enter into a chemical reaction is numerically equal to the mass of substances that are reaction products. The initial ways to practically prove then the assumption of the conservation of the masses were unsuccessful. The fact is that the experiments that were carried out before Lomonosov, were based on the burning of substances. The results of weighing before and after the reaction did not agree with the obvious, but not confirmed in practice, theory. The heating of mercury in air resulted in red scale, and its mass was greater than the mass of the metal entering the reaction. With the ash that appears after the combustion of wood, the result was the opposite, the mass of the product always turned out to be less than the mass of the substance before the reaction.
The merit of Lomonosov is that in order to prove the law of conservation of mass, he first conducted an experiment with closed systems. The simplicity of the experience once again proved the genius of a Russian scientist. Calcined metals Lomonosov placed in a sealed glass vessel. After a successful reaction, the weight of the vessel remained unchanged. And only when the vessel was broken, and air rushed inward, an increase in the mass of the vessel was observed.
A theoretical explanation of the experiment was given by the connecting nature of the metal combustion reaction. The increase in mass occurred due to the addition of oxygen atoms to the oxidation product. Having proved the law of conservation of mass, Lomonosov made a significant contribution to the development of atomic-molecular theory. In practice, he once again proved that atoms are chemically indivisible. The structures of molecules change during the reactions, they exchange atoms with each other, but their total number (of atoms) in a closed system remains unchanged. Accordingly, the total mass of the substance is a constant value.
The law of conservation of mass was the first contribution to the knowledge of a more global natural regularity. Further studies in this direction revealed that in closed systems not only mass conservation occurs. The energy of an isolated system is also a constant value. Any process taking place in an isolated system does not produce and does not destroy either mass or energy. And the revealed regularity was later called: the law of conservation of mass and energy. The works of Lomonosov became only evidence of a special case of the greatest law of nature.
But this does not end the knowledge of the world around us. The works of Einstein advanced science even further; in his theory, he not only proved the relationship between energy and mass, but also made a bold assumption about the possibility of their transformation. What an ordinary schoolboy now seems understandable has been formed in the course of practical experiments and theoretical research over the past three centuries. Scientists in the most diverse fields of science bit by bit put together a powerful platform for proving patterns and understanding the concepts of "energy" and "mass."
Not only physics and chemistry, but also many other sciences actively use the relationship and the principle of conservation of mass and energy. Biology, geography, astronomy find application to the law of conservation of mass and energy. Even philosophy, under the influence of this law, has formed the modern concept of man about being.