Conservation of Mass, Law of
Conservation of Mass, Law of
(or law of conservation of matter), in chemistry. The law of conservation of mass states that the total mass of the reactants in a chemical reaction is equal to the total mass of the products of the reaction.
The law was discovered in 1748 by M. V. Lomonosov. He found experimental confirmation for the law in 1756 in the burning of metals in sealed vessels. The law received wide acceptance in chemistry as a result of the works of A. L. Lavoisier, who provided a formulation of it in 1789.
Quantitative calculations of chemical reactions are based on the law of conservation of mass. From the standpoint of presentday conceptions of the relationship between mass and energy, the law is, strictly speaking, not exact.