Oxidation and reduction – Redox, rusting and iron

The oxidation and reduction occur after the other, called redox reactions. The one reactant gets reduced, and the other one gets reduced. What is an oxidation reaction? In an oxidation reaction, loss of reaction takes place. Whereas in the reduction reaction, the gain of electrons takes place. Both processes occur one after the other, known as an oxidation-reduction reaction. Oxidation reaction can be defined as the removal of hydrogen and the addition of oxygen. And the reduction reaction can be defined as the addition of hydrogen and removal of oxygen. The redox reaction is very useful in real life too. It influences several fields.

Standard reduction potentials table

This  standard reduction potential table is used to give the Eo for specified reduction reactions.

It follows an order that the stronger (more reactive) reductants stay at the top, and the stronger oxidants stay at the bottom.

The reduction potential of a hydrogen half-cell will be negative if:

Remember:- To solve this equation, simply write the first half-reaction of reduction for hydrogen. Then simply, add concentration and pressure. Note that reduction potential is negative.

[reduction]/[oxidation].

2H+ + 2e- → H2.

What is meant by Rusting of iron:-

The rusting of iron is an example of a redox or oxidation-reduction reaction. In the rusting process, iron is used to combine with oxygen in the presence of water. It is an example of an oxidation reaction where oxygen acts as an oxidising agent. The oxygen is also used to get combined with the metal iron, and it is a process of the reduction reaction, and the metal iron behaves as a reducing agent.

What is meant by rust?

The construction of rust is a combination of iron oxides on the surface of iron objects or structures. The rust forms by the process of redox reaction. It takes place between oxygen and iron in an environment containing water as the air contains high moisture levels.

All the reactions involved in rusting of iron

The reaction that occurs in the formation of rust is mentioned below:-

Oxygen is a very active oxidising agent. On the other hand,  iron behaves as a reducing agent. So, the iron atom instantly offers up electrons when revealed to oxygen.

The chemical reaction can be written as:-

Fe → Fe2+ + 2e–

The iron oxidation state is somehow caused by the oxygen atom in the presence of water. 

4Fe2+ + O2 → 4Fe3+ + 2O2-

The mentioned below are the acid-base reactions that occur between the iron cations and the water :-

Fe2+ + 2H2O ⇌ Fe(OH)2 + 2H+

Fe3+ + 3H2O ⇌ Fe(OH)3 + 3H+

Iron hydroxides are also created from the natural interaction and the reaction between the iron cations and hydroxide ions.

O2 + H2O + 4e– → 4OH–

Fe2+ + 2OH– → Fe(OH)2

Fe3+ + 3OH– → Fe(OH)3

How can the rusting of iron be prevented?

To avoid iron rusting, many methods can be applied. Some of them are mentioned below. These are:-

• Electroplating

• Cathodic protection

• Galvanization

• Painting

• Greasing

• Usage of alloys mixed with iron

• Lubrication

The articles of iron are very prone to rust. They easily get rusted in the presence of oxygen and react with the moisture present in the environment. It is very ordinary in every place. The methods mentioned above will help you to protect iron articles.

Conclusion:-

Oxidation and Reduction reactions play a very vital role. The definition of a redox reaction occurs simultaneously. It has real-life uses in industry and manufacturing processes. The gaining of electrons is called Reduction, and the loss of electrons is called Oxidation. In redox reactions, red means reduction and ox means oxidation. Rusting of iron is also an example of redox reactions. In this, iron reacts with oxygen and moisture present in the atmosphere. But there are several ways to prevent the rusting of iron.