The
law of conservation of mass/matter, also known as
law of mass/matter conservation (or the
Lomonosov-
Lavoisier law), states that the
mass of a
closed system will remain constant, regardless of the processes acting inside the system. An equivalent statement is that
matter cannot be created/destroyed, although it may be rearranged. This implies that for any chemical process in a closed system, the mass of the reactants must equal the mass of the products.
The law of "matter" conservation (in the sense of conservation of particles) may be considered as an approximate physical law that holds only in the classical sense before the advent of special relativity and quantum mechanics. Mass is also not generally conserved in open systems, when various forms of energy are allowed into, or out of, the system. However, the law of mass conservation for closed systems, as viewed from their center of momentum inertial frames, continues to hold in modern physics.
This historical concept is widely used in many fields such as chemistry, mechanics, and fluid dynamics.
An early yet incomplete theory of the conservation of mass was stated by Nasir al-Din al-Tusi (1201-1274) in the 13th century. He wrote that a body of matter is able to change, but is not able to disappear.[1]
