An oxidation reduction reaction, sometimes known as a redox reaction, is when both oxidation and reduction occur. There are many examples of oxidation reduction in everyday life, from plant and animal life to the domestic and industrial worlds. In an oxidation reduction reaction, the oxidation number of atoms or molecules changes as electrons are transferred between them. Oxidation involves a decrease in electrons, while reduction involves an increase. Redox reactions are found in many familiar places including plants, animals, metals, foods and machines.
Photosynthesis in plants is a common everyday example of oxidation reduction. Through photosynthesis, plants use light to transform carbon dioxide and water into chemical energy, releasing oxygen along the way. The carbon dioxide undergoes reduction to produce glucose, while the water is oxidised, producing molecular oxygen. Photosynthesis, and therefore the redox reaction, is essential for plant life.
Respiration in animals is an example of oxidation reduction. Respiration involves similar processes to photosynthesis, but in reverse. During respiration, glucose sugars are oxidised to form carbon dioxide, while oxygen undergoes reduction to form water. Respiration is a cellular process and is essential to animal life, as it is a key element in the ability to turn food into energy.
While oxidation reduction allows humans to gain energy from food, food itself is also subject to redox reactions when not being eaten. Oxidation reduction makes food items go off, on account of oxidation. Food manufacturers sometimes attempt to inhibit this process using preservatives. The preservatives encourage reduction, countering the oxidisation and slowing the rate at which a food product deteriorates.
One of the most visible redox reactions in daily life is rusting. When certain metals react with oxygen, oxidisation occurs, causing an oxide to form. In the case of iron this is iron oxide, which is what we typically call rust. Oxidisation can cause metals to corrode, which has serious implications for any industries producing metal products. When some metals, such as copper and silver, undergo oxidisation, their colour changes.
Oxidisation Reduction is a vital element in many industrial processes. A simple battery involves a redox reaction, with two connected chemicals, one with an oxidising and one with a reducing solution, creating an electric current. Combustion is another common oxidation reduction reaction application, including the burning of fats, wood and coal. Combustion, in turn, facilitates explosions, from fuel, to firearms, fireworks and bombs. Space shuttle rockets also rely on the processes of oxidation reduction for thrust.