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 of substances will remain constant, regardless of the processes acting inside the system. An equivalent statement is that matter cannot be created nor destroyed, although it may change form. 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 mass/matter conservation may be considered as an approximate physical law that holds only in the classical sense before the advent of special relativity and quantum mechanics. The name Lomonosov may refer to: Mikhail Lomonosov, a polymath and writer of Imperial Russia Lomonosov Gold Medal, an annual award given by the Russian Academy of Sciences Lomonosov, Russia, a city named for Mikhail Lomonosov (formerly Oranienbaum) This is a disambiguation page — a navigational aid which lists other... Antoine-Laurent de Lavoisier (August 26, 1743 - May 8, 1794) was a French nobleman prominent in the histories of chemistry, finance, biology, and economics. ... This article or section is in need of attention from an expert on the subject. ... In thermodynamics, a closed system, as contrasted with an isolated system, can exchange heat and work, but not matter, with its surroundings. ... This article is about matter in physics and chemistry. ... For a less technical and generally accessible introduction to the topic, see Introduction to special relativity. ... Fig. ...

This historical concept is widely used in many fields such as chemistry, mechanics, and fluid dynamics. For other uses, see Chemistry (disambiguation). ... For other uses, see Mechanic (disambiguation). ... Fluid dynamics is the sub-discipline of fluid mechanics dealing with fluids (liquids and gases) in motion. ...

Historical development and importance

The law of conservation of mass was first clearly formulated by Antoine Lavoisier in 1789, who is often for this reason (see below) referred to as the father of modern chemistry. However, Mikhail Lomonosov (1748) had previously expressed similar ideas and proved them in experiments. Historically, the conservation of mass and weight was kept obscure for millennia by the buoyant effect of the Earth's atmosphere on the weight of gases, an effect not understood until the vacuum pump first allowed the effective weighing of gases using scales. Once understood, conservation of mass was of key importance in changing alchemy to modern chemistry. When scientists realized that substances never disappeared from measurement with the scales (once buoyancy had been accounted for), they could for the first time embark on quantitative studies of the transformations of substances. This in turn led to ideas of chemical elements, as well as the idea that all chemical processes and transformations (including both fire and metabolism) are simple reactions between invariant amounts/weights of these elements. Antoine-Laurent de Lavoisier (August 26, 1743 – May 8, 1794), the father of modern chemistry [1], was a French nobleman prominent in the histories of chemistry, finance, biology, and economics. ... Year 1789 (MDCCLXXXIX) was a common year starting on Thursday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Monday of the 11-day slower Julian calendar). ... For other uses, see Chemistry (disambiguation). ... Mikhail Vasilyevich Lomonosov Mikhail Vasilyevich Lomonosov (Михаи́л Васи́льевич Ломоно́сов) (November 19 (November 8, Old Style), 1711 – April 15 (April 4, Old Style), 1765) was a Russian writer and polymath who made important contributions to literature, education, and science. ... Events April 24 - A congress assembles at Aix-la-Chapelle with the intent to conclude the struggle known as the War of Austrian Succession - at October 18 - The Treaty of Aix-la-Chapelle is signed to end the war Adam Smith begins to deliver public lectures in Edinburgh Building of...

Generalization

Main article: Conservation of mass in special relativity

Main article: Conservation_of_energy#Modern physics

In special relativity, the conservation of mass does not apply. Conservation of mass in the theory of special relativity depends on the definition of mass/matter used. ... In physics, the conservation of energy states that the total amount of energy in an isolated system remains constant, although it may change forms, e. ...

The principle that the mass of a system of particles is equal to the sum of their masses, even though true in classical physics, is false in special relativity. The mass-energy equivalence formula implies that bound systems have a mass less than the sum of their parts. The difference, called a mass defect, is a measure of the binding energy — the strength of the bond holding together the parts (in other words, the energy needed to break them apart). The greater the mass defect, the larger the binding energy. The binding energy is released when the parts combine to form the bound system. ^[1] For a less technical and generally accessible introduction to the topic, see Introduction to special relativity. ... 15ft sculpture of Einsteins 1905 E = mc² formula at the 2006 Walk of Ideas, Germany In physics, mass-energy equivalence is the concept that all mass has an energy equivalence, and all energy has a mass equivalence. ... Binding energy is the energy required to disassemble a whole into separate parts. ...

Other violations of the conservation of mass can occur in special relativity. For example, when matter is converted to massless energy according to E = mc². As another example, when an atom emits a photon (which is massless), the atom's mass is decreased by E/c² where E is the photon's energy. The mass of closed (isolated) systems can diminish by emission of photons, even if the photons remain inside the system.^[2]

In special relativity, the conservation of mass can also not be cast as a statement of conservation of energy. A system of two photons can be massless or have an inertial mass up to 2E/c², where E is each photon's energy (assumed equal), as a function of relative momentum orientation for the photons. So, independently of the energy content being constant at 2E, the total mass may vary from zero to 2E/c².^[3]

The conservation of mass also does not apply to particles created by pair production. Pair production refers to the creation of an elementary particle and its antiparticle, usually from a photon (or another neutral boson). ...

References

1. ^ Kenneth R. Lang, Astrophysical Formulae, Springer (1999), ISBN 3540296921
2. ^ Lev Okun, The Concept of Mass, Physics Today, June 1989.
3. ^ Edwin Floriman Taylor, John Archibald Wheeler, Spacetime Physics: introduction to special relativity, W.H.Freeman & Co Ltd (1992), ISBN 0716723271

See also

• Continuity equation in fluid dynamics
• Conservation of energy
• Mass balance