What is CUO + H2

The reduction is a type of chemical reaction that is defined differently. It occurs (depending on the definition) together with the oxidation. Both phenomena never run independently of one another and are collectively referred to as the redox reaction.

The current definition of the term is: A substance that releases electrons during a reaction is oxidized, a substance that accepts electrons is reduced.

Outdated definition of reduction:

1. Reduction: release of oxygen
In the simplest sense, a reduction is that Release of oxygen. If z. B. red mercury oxide is split into mercury and oxygen, it is a reduction:

A second example: If copper (II) oxide (CuO) is heated in a stream of hydrogen, metallic copper (Cu) is produced because the hydrogen and the oxygen in the copper (II) oxide form water; the copper (II) oxide is deprived of oxygen.

A third example: If you heat copper (II) oxide together with carbon (C) in a test tube under a gas burner, you get copper and carbon dioxide (CO2). The cupric oxide has converted to copper and the oxygen is now in the carbon dioxide. (The carbon dioxide released during the experiment can be detected with lime water. see carbon dioxide # proof)

2. Reduction: absorption of hydrogen
At a higher level, reduction is defined as the uptake of hydrogen (and oxidation as the release of hydrogen). Note: Here, too, electrons are absorbed. This means that a proton and an electron are absorbed. However, because hydrogen is not very electronegative, every other atom pulls the hydrogen electron towards itself when it forms a connection with "H". (So ​​it is more an absorption of electrons than an absorption of hydrogen). B. Acetaldehyde absorbs hydrogen, the result is ethanol:

This concept of reduction is especially important for biological processes. In many metabolic pathways in a cell, a reduction takes place through the transfer of hydrogen. The cell has even developed special coenzymes for this, e.g. B. NAD, NADP or FAD, which are able to transfer hydrogen from one compound to another.

Current definition of reduction: uptake of electrons / reduction of the oxidation number
Finally, on an even higher level, reduction is understood to mean the uptake of electrons. If z. B. an iron nail is placed in a copper sulfate solution, a red-brown deposit of metallic copper forms on the nail because the iron atoms give electrons to the copper ions. The copper is reduced (the iron oxidizes).

In this general Definition occurs the reduction always together with the oxidation on:

Redox equation:

The iron, which is itself oxidized during the redox reaction, is also called reducing agent in this context, because its presence makes the reduction of copper possible in the first place.

Reduction always means a decrease in the oxidation number and thus the acceptance of electrons. Oxidation, on the other hand, means the release of electrons and thus an increase in the oxidation number.

Category: Chemical reaction