Gained and Lost in Redox Reactions

Redox is a combination of the reduction and oxidation reaction. Redox reactions are chemical reactions in which electrons are transferred from one material to another. Both oxidation and reduction occur simultaneously in these processes. Changes in the oxidation states of the reacting species can be used to identify this electron transfer.

Redox Reactions Types

There are various types of redox reactions, each of which is described below:

• Reaction of Decomposition

It entails breaking down a substance into its constituent parts. The following are examples of these types of reactions:

Na2CO3.→ CO2 + Na2O

2H2O → 2H2 + O2

2NaH → 2Na + H2

The reactions listed above are the consequence of the procedure of breaking down smaller chemical molecules.

AB → A + B

There is a single case that confirms that none of the decomposition reactions are redox reactions.

CaCO3 → CaO + CO2 is an example.

• Reaction of Combination

Chemical reactions in this category include the mixing of two compounds to generate a single compound in the form of A + B →  AB.

Consider the following:

4Fe + 3O2→2Fe2O3

• Displacement Reaction

An atom or an ion of a compound gets replaced by an atom or an ion of a different element in this type of reaction.

This reaction can be expressed as X + YZ  → XZ + Y.

Cl2 + 2NaBr  →2NaCl + Br2 is an example.

• Reaction of Metal Displacement

A metal in the compound is replaced  by another metal in a metal displacement reaction.

These reactions are used in metallurgical operations to extract pure metals from their ores.

CuSO4+Zn  →ZnSO4 + Cu is an example.

Reaction of Non-Metallic Displacement

We can find hydrogen displacement reactions in non-metal displacement reactions, as well as oxygen displacement reactions on rare occasions.

• Disproportionation Reaction

The reactant is both oxidised and decreased in disproportionation reactions.

As an example, P4 + 3H2O + 3NaOH  → PH3 + 3NaH2PO2

What is the Oxidation Process?

An oxidation reaction is the addition of oxygen or a more electronegative element to a molecule or the removal of hydrogen or a more electropositive element from a material.

Some instances of oxidation processes are as follows:

2S(s) + O2 (g) → SO2 (g) 

CO2 (g) + 2H2O + CH4 (g) + 2O2 (g) (l)

What is the Reduction Reaction?

Reduction reactions, like oxidation events, are defined as electron gains. During a chemical process, any material that acquires an electron is reduced.

A reduction reaction is the addition of hydrogen or another more electropositive element to a substance, or the removal of a more electronegative element like oxygen.

Some reduction reactions are listed below:

CH3CH3  → 2CH2CH2 (g) + H2 (g) 

2FeCl2 (aq) + 2HCl  → 2FeCl3 (aq) + H2 (g) 

When we look at the aforementioned reactions closely, we can see that they all have both reduction and oxidation reactions.

As the electronegative element chlorine is eliminated from FeCl3, it undergoes a reduction process. In the same reaction, hydrogen is oxidised due to the presence of chlorine, an electronegative element.

Oxidising and Reducing Agents

Oxidising Agent

In a chemical reaction, an oxidising substance (oxidant) obtains electrons and is reduced. It’s also referred to as an electron acceptor. Because it will gain electrons and be reduced, the oxidising agent is normally in one of its higher potential oxidation states.

Definition

An oxidising agent (sometimes called an oxidizer or oxidant) is a chemical species that oxidises other substances, causing them to lose electrons and hence elevate their oxidation state.

• They are chemical compounds whose atoms in a chemical process remove at least one electron from another atom.

• In a chemical process, an oxidising agent is a substance that transfers at least one electronegative atom to a chemical species.

Examples

The following are some instances of oxidising agents.

• Hydrogen halides (such as chlorine and fluorine)
• Oxygen
• Peroxide (H2O2) 
• Nitrate of potassium
• Nitric oxide (NOx)

Reducing Agent

In a chemical reaction, a reducing agent (reductant) loses electrons and is oxidised. It is known as an electron donor when it is in one of its lower possible oxidation states. When a reducing substance loses electrons in a redox reaction, it is oxidised.

Definition

In a redox reaction, a reducing agent loses electrons to other compounds and is oxidised to a higher valency state.

• In an oxidation-reduction reaction, a reducing agent is one of the reactants that reduces the other reactant by releasing electrons.
• The reduction process cannot take place if the reducing agent does not pass electrons to other substances in the reaction.

Examples

The following are some common examples of reducing agents.

• Sodium (Na) –
• Iron-Fe
• Zinc- Zn
• Al, as well as non-metals such as C, S, and H2.
• Hydracids like HCl, HI, HBr, and H2S
• Hydrochloric acid
• Compounds containing sulfite

Conclusion

A redox reaction, also called an oxidation-reduction reaction, is a chemical reaction in which one of the reactants is oxidised while the other is reduced. A compound’s oxidation can be described in a variety of ways, one of which is the gain of links to oxygen, and another is the loss of electrons. Similarly, the acquisition of hydrogen or the gain of electrons are two valid definitions of reduction (the reverse of oxidation).

In our daily lives, redox reactions are crucial. Redox reactions are essential in our bodies to generate ATP to fuel our metabolism and muscles, and combustion reactions that generate heat and electricity. Redox reactions include the burning of natural gas, oil, gasoline, or wood.