Oxidation and Reduction
- Oxidation and oxidizing agent
- Reduction and reducing agent
- Significance of oxidation and reduction in everyday life
These notes are based on the chapter Chemical Reactions and Equations from NCERT book based on CBSE syllabus.
Oxidation
Addition of oxygen or non-metallic element or removal of hydrogen or metallic element from a compound is known as oxidation. Elements or compounds in which oxygen or non-metallic element is added or hydrogen or metallic element is removed are called to be oxidized.
So, oxidation can involve any of the following:
- Addition of oxygen
- Addition of non-metallic element
- Removal of hydrogen
- Removal of metallic element
Oxidizing agent
Compounds which can add oxygen or a non-metallic compound or remove hydrogen or metallic element are known as oxidizing agents.
Reduction
Addition of hydrogen or metallic element or removal of oxygen or non-metallic element from a compound is called reduction. The compound or element which goes under reduction is called to be reduced. So, reduction can involve any of the following:
- Addition of hydrogen
- Addition of metal
- Removal of oxygen
- Removal of non-metal
To make it easier to understand, here is table to show comparision between oxidation and reduction.
| Oxidation | Reduction |
|---|---|
| Addition of oxygen | Addition of hydrogen |
| Addition of non-metallic element | Addition of metal |
| Removal of hydrogen | Removal of oxygen |
| Removal of metallic element | Removal of non-metallic element |
Reducing agent
Compounds or elements which can cause reduction are called reducing agents.
In a chemical reaction, both oxidation and reduction take place simultaneously and such reactions are also known as REDOX REACTIONS. In the word REDOX, Red stands for reduction and Ox stands for oxidation.
Example: When iron reacts with air, it forms iron oxide (rust). This reaction is also called Rusting of Iron.
4Fe + 3O2 → 2Fe2O3
In this reaction, oxygen is added to iron, thus, iron is oxidized. Here oxygen is oxidizing agent.
Example: When cupric oxide reacts with hydrogen, it gives copper and water.
CuO + H2 → Cu + H2O
In this reaction, oxygen is removed from copper and oxygen is added to hydrogen. So, cupric oxide is reduced to copper and hydrogen is oxidized to water. Cupric oxide is oxidizing agent and hydrogen is reducing agent.
Example: When sodium hydroxide reacts with hydrochloric acid, it gives sodium chloride and water.
NaOH + HCl → NaCl + H2O
In this reaction, sodium hydroxide is reduced to sodium chloride since hydrogen is removed from sodium hydroxide. Hydrochloric acid is oxidized to water, since oxygen is added to hydrogen chloride and non-metallic element chloride is removed. Sodium hydroxide is oxidising agent and hydrochloric acid is reducing agent.
In this reaction oxidation and reduction both takes place simultaneously, thus it is an example of redox reaction.
Significance of Oxidation Reduction in Everyday Life:
- Respiration is oxidation reaction in which food is oxidized to produce energy.
- Iron gets oxidized to form rust, which leads to corrosion of iron in the long run.
- Most of the metals react with atmospheric oxygen and it leads to formation of a layer on the metal article. The metal gets corroded in the long run.
- Rusting of iron can be prevented by painting the iron article. This can also be prevented by applying a layer of zinc over iron article. This process is known as galvanization.
- Fried food gets oxidized when exposed to air. This spoils the taste of the food and the food becomes unfit for consumption. The spoiling of fried food because of oxidation is called rancidity. Fried food is often packed in airtight packets to prevent rancidity.
- We are able to utilize various types of fuel because of oxidation. Oxidation of fuel helps in producing energy.