Oxidation: An Introduction
Oxidation Reactions are the most significant chemical reactions that affect our everyday life. The most chemical reactions that we come across in our daily life, and various others which are out of our everyday experience are either oxidation or reduction reactions.
Oxidation reactions are crucial to keep our life moving. In a simple manner, an oxidation reaction can be defined as a reaction where oxygen is added to a compound and reduction is the removal of oxygen from any compound. The oxidation reaction is always coupled with a reduction reaction, that is because when one compound gets oxidised some other compound invariably gets reduced, hence these reactions are termed redox reactions.
Effects of Oxidation reaction in Everyday Life
Have you observed the effects of oxidation reactions in everyday life? Perhaps you have, but you are not aware of them as an oxidation reaction. Let me give an example of an oxidation reaction that might be very familiar-
Rusting:
We have all seen iron catching rust. Rusting is a form of corrosion of metal. Corrosion occurs due to the degradation of a metal by the action of air and moisture in the environment. It is a result of the oxidation of the metal.
Iron catches rust because it gets oxidised in presence of air and water to form hydrated iron oxide (Fe2O3.xH2O). The iron oxide forms a reddish-brown covering on the metal surface.
4Fe + 3O2 + 2xH2O —> Fe2O3.xH2O (Rust)
Similar corrosion due to the formation of metal oxide is observed on silver (black silver oxide coating) and copper (green coating).
Rusting or corrosion damages structures with metal bodies over a long time. Bodies of cars, bridges, railways, iron railings and ships catch rust. Coating the surface of the metal with paint or enamel can save them from corroding.
Another common effect of an oxidation reaction in everyday life is the rotting of food. Foods containing fats or oil become rancid if exposed to the air for a long time. This is due to slow aerial oxidation of the fatty acids present in the food, resulting in unpleasant odour and bad taste. Food items change colour and texture along with taste and smell upon exposure to the air due to atmospheric oxidation and this phenomenon is called 'rancidity'.
Combustion
Combustion is one of the most important oxidation reactions. All combustion reactions produce energy as a by-product, they are called exothermic reactions specifically due to the emission of heat energy.
As we know, our society is dependent on energy. Fuels such as kerosene, petroleum, coal, wood and charcoal all combust in presence of air, producing heat. Natural gas containing methane undergoes combustion in presence of excess oxygen to produce carbon dioxide and water.
Coals are burnt in thermal power plants to produce electricity and natural gas is used for cooking. Thus, we can see how vital role redox reactions play in our quality of life.
Thermal energy produced from the burning of fuel not only keeps our economy running, but thermal energy is what keeps us warm and alive. Our body needs thermal energy produced from breaking down food to maintain its function. Human body can be imagined as a machine which burns and oxidises all the foodstuff supplied to it and generates energy. Carbohydrates or sugar such as glucose (C6H12O6), fructose and starch are the energy source of the body. Sugars are combusted with oxygen giving out carbon dioxide and water, along with heat.
CH4 + 2O2 —> CO2 + 2H2O
C6H12O6 + 6O2 —> 6CO2 + 6H2O + energy
Respiration supplies oxygen to the cells, where glucose is oxidised accompanied by the production of carbon dioxide and water to provide energy to the cells to perform all the essential functions necessary for the maintenance of life. Carbon dioxide produced in cells is subsequently expelled from the body through exhalation.
Although combustion has considerable utility, its harmful effect on our lives should be given proper attention. Combustion of fossil fuel produces toxic fumes containing harmful gases like sulphur dioxide, sulphur trioxide, nitrogen oxides and carbon monoxide. Fumes and smoke from car exhaust and furnaces when released into the atmosphere cause severe air pollution. It directly harms our bodies and deteriorates our health.
Key Features
The oxidation reaction is the addition of oxygen to a compound.
The reduction reaction is the removal of oxygen from a compound.
Combustion is one of the most important oxidation reactions.
Interesting Facts
Fish can soak oxygen dissolved in water using gills for respiration.
Plants absorb oxygen through stomata in their leaves.
FAQs on Oxidation Reaction in Everyday Life
1. What is the difference between burning and combustion?
Burning is the form of combustion that is accompanied by the evolution of gas and marked by flame; combustion is simply an oxidation reaction that produces energy. Combustion leading to fire is burning, but all combustions do not cause a flame.
2. How oxygen is supplied to the cell for respiration?
Human beings inhale oxygen, which enters the lung and travel through numerous alveoli (tiny air sacs). The oxygen is diffused into the blood from these air sacs, which is then taken to the cells. The oxygen from the lungs is exchanged with blood, where it binds with haemoglobin in the red blood cell, and the oxygen bound haemoglobin is taken to all the cells where it is unloaded. The waste carbon dioxide is picked up from the cells and transported back to the lungs for exhalation.
3. What are antioxidants?
Antioxidants are compounds that can inhibit oxidation. It is often used in foods to prevent staling. These chemicals protect the food item by themselves from undergoing oxidation. Some examples of antioxidants are BHA (Butylated Hydroxyanisole) and BHT (Butylated Hydroxytoluene).