The law of conservation of mass was first discovered by Russian scientist Lomonosov in 1756. Through a large number of quantitative experiments, Lavoisier discovered that in chemical reactions, the sum of the masses of each substance participating in the reaction is equal to the sum of the masses of each substance produced after the reaction.

This law is called the Law of Conservation of Mass. Also known as the law of the immortality of matter. It is one of the universal fundamental laws of nature.

In any system that is isolated from its surroundings, no matter what changes or processes occur, its total mass always remains the same. In other words, any change, including chemical reactions and nuclear reactions, cannot eliminate matter, but only changes the original form or structure of matter, so this law is also called the law of the immortality of matter.

Extended information:

1. Related explanations

During a chemical reaction, the types of atoms do not change before and after the reaction, and the number of atoms does not increase or decrease. The quality has not changed either. Therefore, the total mass of each substance before and after the chemical reaction must be equal.

1. "Must not change" in chemical changes: the type of atom, the number of atoms, the atomic mass, the type of element, the mass of the element and the total mass of each substance before and after the reaction must not change.

2. "Definite change" in chemical changes; the types of molecules and substances must change.

3. "Possible changes" in chemical changes: the number of molecules may change, and the valence of elements may change.

2. Scope

1. The applicable scope of the law of conservation of mass is all chemical changes, including most physical changes.

2. The law of conservation of mass reveals the conservation of mass rather than the conservation of other aspects. The volume of an object is not necessarily conserved.

3. In the law of conservation of mass, "what participates in the reaction" is not the simple addition of the masses of each substance, but refers to the part of the mass that actually participates in the reaction. Some of the reactants may not participate in the reaction.

4. Corollary to the law of conservation of mass: In a chemical reaction, the total mass of each substance before the reaction is equal to the total mass of each substance after the reaction.

Baidu Encyclopedia-Law of Conservation of Mass