Oxidizing agent: what is it, the strongest, examples

A oxidizing agent is a chemical substance that has the ability to subtract electrons from another substance (reducing agent) that donates or loses them. It is also known as an oxidizing agent to that element or compound that passes electronegative atoms to another substance.

When studying chemical reactions, all the substances involved and the processes that occur in them must be taken into account. Among the most important are the oxidation-reduction reactions, also called redox, which involve the transfer or transfer of electrons between two or more chemical species.

In these reactions two substances interact: reducing agent and the oxidizing agent. Some of the oxidizing agents that can be observed more frequently are oxygen, hydrogen, ozone, potassium nitrate, sodium perborate, peroxides, halogens and permanganate compounds, among others.

Oxygen is considered the most common of the oxidizing agents. An example of these organic reactions involving the transfer of atoms is combustion, which is a reaction produced between oxygen and some other oxidizable material.

What are the oxidizing agents?

In the oxidation half-reaction the oxidizing agent is reduced because, upon receiving electrons from the reducing agent, a decrease in the charge value or oxidation number of one of the atoms of the oxidizing agent is induced.

This can be explained by the following equation:

2Mg (s) + O ₂ (g) → 2MgO (s)

It can be seen that magnesium (Mg) reacts with oxygen (O2), and that oxygen is the oxidizing agent because it subtracts electrons from magnesium - that is, it is reducing - and magnesium becomes, in turn, in the reducing agent of this reaction.

Similarly, the reaction between a strong oxidizing agent and a strong reducing agent can be very dangerous because they can interact violently, so they must be stored in separate places.

What factors define the strength of an oxidizing agent?

These species are distinguished according to their"strength". That is, the weakest are those who have a lower ability to subtract electrons from other substances.

In contrast, the strongest have greater ease or ability to"pluck"these electrons. For its differentiation, the following properties are considered:

Atomic radio

It is known as half the distance separating the nuclei from two atoms of adjacent or"neighboring"metal elements.

Atomic radii are usually determined by the force with which the most superficial electrons are attracted to the nucleus of the atom.

Therefore, the atomic radius of an element decreases in the periodic table from bottom to top and from left to right. This implies that, for example, lithium has a significantly larger atomic radius than fluorine.

Electronegativity

The electronegativity it is defined as the ability of an atom to capture electrons belonging to a chemical bond. As electronegativity increases, the elements present an increasing tendency to attract electrons.

In general terms, electronegativity increases from left to right in the periodic table and decreases while the metallic character grows, with fluorine being the most electronegative element.

Electronic affinity

It is said to be the variation of the energy that is recorded when an atom receives an electron to generate an anion; that is, it is the ability of a substance to receive one or more electrons.

As the electronic affinity increases, the oxidative capacity of a chemical species increases.

Ionization energy

It is the minimum amount of energy that is needed to pull an electron out of an atom or, put another way, it is a measure of the"force"with which an electron is bound to an atom.

The larger the value of this energy, the more difficult the detachment of an electron becomes. Thus, the ionization energy enlarges from left to right and is reduced from top to bottom in the periodic table. In this case, the noble gases have large values ​​of ionization energies.

The strongest oxidizing agents

Taking into account these parameters of the chemical elements, it is possible to determine which are the characteristics that the best oxidizing agents must have: high electronegativity, low atomic radius and high ionization energy.

That said, it is considered that the best oxidizing agents are the elemental forms of the most electronegative atoms, and it is observed that the weakest oxidizing agent is metallic sodium (Na +) and the strongest is the elemental fluorine molecule (F2), which is capable of oxidizing a large quantity of substances.

Examples of reactions with oxidizing agents

In some oxidation-reduction reactions it is easier to visualize the transfer of electrons than in the others. Below we will explain some of the most representative examples:

Example 1

The decomposition reaction of mercury oxide:

2HgO (s) → 2Hg (l) + O ₂ (g)

In this reaction, mercury (oxidizing agent) is distinguished as the electron receptor of oxygen (reducing agent), decomposing into liquid mercury and gaseous oxygen when heated.

Example 2

Another reaction that exemplifies oxidation is that of sulfur burning in the presence of oxygen to form sulfur dioxide:

S (s) + O ₂ (g) → SO ₂ (g)

Here it can be seen that the oxygen molecule is oxidized (reducing agent), while the elemental sulfur is reduced (oxidizing agent).

Example 3

Finally, the combustion reaction of propane (used in gas for heating and cooking):

C ₃ H ₈ (g) + 5O ₂ (g) → 3CO ₂ (g) + 2H ₂ O (l)

In this formula you can observe the reduction of oxygen (oxidizing agent).

References

1. Reducing agent. Retrieved from en.wikipedia.org
2. Chang, R. (2007). Chemistry, Ninth edition (McGraw-Hill).
3. Malone, L. J., and Dolter, T. (2008). Basic Concepts of Chemistry. Recovered from books.google.co.ve
4. Ebbing, D., and Gammon, S. D. (2010). General Chemistry, Enhanced Edition. Recovered from books.google.co.ve
5. Kotz, J., Treichel, P., and Townsend, J. (2009). Chemistry and Chemical Reactivity, Enhanced Edition. Recovered from books.google.co.ve