What is Law of conservation of matter

What Does Law of conservation of matter Mean

We explain what the law of conservation of matter or the Lomonosov-Lavoisier Law is. History, background and examples.

Antoine-Laurent Lavoisier (1743-1794), known as the father of chemistry.

Law of conservation of matter

The law of conservation of matter , also known as the law of conservation of mass or simply as the Lomonosov-Lavoisier law (in honor of the scientists who postulated it), is a principle of chemistry that states that matter is neither created nor it is destroyed during a chemical reaction , it just transforms.

This means that the amounts of the masses involved in a given reaction must be constant, that is, the amount of reactants consumed is equal to the amount of products formed, even if they have been transformed into each other.

This fundamental principle of the natural sciences was postulated by two scientists simultaneously and independently: the Russian Mikhail Lomonosov in 1748 and the French Antoine Lavoisier in 1785. It is striking that this occurred before the discovery of the atom and the postulation of the atomic theory , with which it is much easier to explain and illustrate the phenomenon.

The exception to the rule is nuclear reactions , in which it is possible to convert mass into energy and vice versa.

Along with the equivalence between mass and energy, the law of conservation of matter was key to understanding contemporary chemistry.

See also: Exothermic reaction

Background of the Law of conservation of matter

The chemistry of those years understood the reaction processes in a very different way from the current one, in some cases even affirming the opposite of what this law proposes.

In the 17th century Robert Boyle experimented with weighing metals before and after allowing them to oxidize . This scientist attributed the change in the weight of these metals to the gain of matter, ignoring that the metallic oxide that was formed came from the reaction of the metal with the oxygen in the air .

Discovery of the Law of Conservation of Matter

The experiences that led Lavoisier to the discovery of this principle have to do with one of the main interests of chemistry of the time: combustion . By heating various metals, the Frenchman found that they gained mass when calcined if they were left exposed to the air, but that their mass remained the same if they were in closed containers.

Thus, he deduced that this extra amount of mass came from somewhere. He proposed, then, his theory that the mass was not created, but taken from the air . Therefore, under controlled conditions, the amount of mass of the reactants can be measured before the chemical process and the amount of mass after, which must necessarily be identical, although the nature of the products is no longer so .

Example of the Law of Conservation of Matter

A perfect example of this law is the combustion of hydrocarbons , in which fuel can be seen to burn and “disappear”, when in reality it will have been transformed into invisible gases and water.

For example, when burning methane (CH 4 ) we will have the following reaction, whose products will be water and invisible gases, but with an identical number of atoms as the reactants:

xIt can help you: Principle of conservation of energy

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