Oxidation and Reduction. Oxidation and Reduction

In the oxidation reaction, the loss of electrons occurs, while the reduction reaction consists of gaining electrons.

THE Oxidation it can occur in three circumstances: when oxygen is added to the substance, when a substance loses hydrogen, or when the substance loses electrons. Example: fruit salads tend to darken when they come into contact with the air, because oxygen acts promoting the oxidation of fruit. A tip for this not to happen is to add lemon or orange juice, as the vitamin C present in citrus fruits prevents the oxidizing action of oxygen on the salad.
THE Reduction, in turn, is the opposite and also occurs in three ways: when a substance loses oxygen, when it gains hydrogen, or when it gains electrons. Example: when copper oxide (black) is placed in an appropriate apparatus (chamber) for its reduction to occur, the hydrogen gas enters contact with the super heated copper oxide and as a result it loses oxygen and gradually turns pink as it is being reduced to copper.
Oxide-Reduction Reaction

: It is known that oxidation and reduction occur together in the same chemical reaction. This phenomenon is called Redox reaction or oxidoreduction. Oxidoreductions are reactions that transfer electrons between substances causing the oxidation number (nox) of one substance to increase while the nox of another substance decreases. This process should not be confused with ionic bonds (in which electrons are transferred from one substance to another) but rather as a process of oxidation of one substance and the reduction of another. We can then say that in a reaction the substance that loses electrons and undergoes oxidation is called the reducing agent, while the substance that gains electrons and undergoes reduction is called the oxidizing agent.
Some of these reactions are very useful for the industry. Iron, for example, is extracted by combining iron ore with carbon monoxide (CO) in a blast furnace. In this reaction, the ore loses oxygen to form iron (Fe) and CO receives oxygen to form CO₂ (carbon dioxide). Rust is one of the results of a redox reaction, in which iron oxidizes to form iron oxide (rust), and oxygen in the air is reduced.
Another example of a redox reaction is that of silver in contact with air. Silver objects tend to lose their shiny appearance over time, becoming dull and dark in color. This fact occurs because the silver atoms on the object's surface react with other substances, such as oxygen. We then say that the silver has oxidized, that is, it has undergone an oxidation-reduction reaction.

By Líria Alves
Graduated in Chemistry

Source: Brazil School - https://brasilescola.uol.com.br/quimica/oxidacao-reducao.htm