Law of Conservation of Matter

What is the law of conservation of matter?

The law of conservation of matter is the one that holds that, within a closed system, the amount of matter involved in a chemical reaction is constant.

By closed system we mean an environment that isolates the components involved in the reaction from the outside, such as a sealed container.

When the transformation is carried out through a physical process, no alteration is observed in the masses.

In other words, if we fill a container with water and freeze it, the amount of water does not increase or decrease, it only changes its state from liquid to solid.

The process does not alter the mass of the elements that participate in the reaction, it only causes a new organization in its structure. We are going to have the same amount of matter at the beginning and at the end of said reaction.

The statement that best describes what this law postulates is:

“In nature nothing is created or destroyed, everything is transformed” (A. Lavoisier, 1785)

The law of conservation of matter was developed in the 18th century thanks to two scientists, Mikhail Lomonosov and Antoine Lavoisier, who simultaneously reached similar conclusions.

Numerous facts of our day to day show what sustains this basic principle of chemistry.

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Examples of the law of conservation of matter

Here are some situations that confirm this law:

Fruit decomposition

The reduction in the size of the food as it degrades is notable. This matter is transformed into gases that are released into the environment.

Melt ice

Leaving a glass of ice at room temperature melts the ice. The amount of substance remaining in the container is the same, only its state is altered.

Boil water

The boiling of water also serves as an example, since when it boils, the water is consumed and transformed into steam, which remains in the environment.

Rusty objects

Metallic objects, usually iron, rust due to their exposure to oxygen. The oxygen reacts with the metal generating an oxide layer on its surface.

Rusty chain with noisy background of sky and trees

Compound formation

In the formation of water, two hydrogen molecules (2 Htwo) react with an oxygen molecule (Otwo) giving rise to two water molecules (2HtwoEITHER). As we see in the image, the total number of atoms between reactants and products does not vary, there are four hydrogen atoms and two oxygen atoms on each side of the reaction.

substance formation

See also:

  • Matter
  • Changes in the states of the matter

Discovery of the law of conservation of matter

The discovery of this law takes place in the eighteenth century due to the existing concern in the scientific community about the loss of matter in certain processes such as combustion.

In 1748 Mijaíl Lomonosov, an outstanding scholar in different arts and sciences, made the first formulation of this law.

“In a chemical reaction matter is conserved, the initial mass being equal to the resulting mass” (M. Lomonosov, 1748)

Years later, in 1785, Antoine Lavoisier, a French lawyer, economist and scientist, reformulated the law, adding new nuances.

“Elements participating in a chemical reaction each retain their own mass after the reaction” (A. Lavoisier, 1785)

For this reason the law of conservation of matter is also known as the Lomonosov-Lavoisier law.

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Both scientists used, for the first time, methods to measure and weigh accurately, which was an important advance for chemistry and contributed to the discovery of its fundamental laws.