When we talk about chemical reactions, we usually discuss the breakage and formation of bonds, gain and loss of electrons, and conversion from one state of matter to another. If we look closely, we might observe hundreds of chemical reactions taking place in our vicinity. You may find it quite surprising that almost one-third of the chemical reactions taking place in the surroundings fall under the category of redox reactions. Redox reactions include different types of chemical changes which occur in nature. The chemical changes may occur slowly, rapidly, or abruptly; say, for example, rusting of iron takes a long time whereas the cleaning of dishes can be done rather quickly. Isn’t it?
In this article, we are going to discuss various real-life examples of redox reactions taking place in our environment and homes.
Cellular respiration which is the ultimate source of energy in human beings encompasses a series of redox reactions. So, the food that we consume is converted into energy by redox reactions only.
During the process of respiration, the carbon-dioxide is reduced whereas the water is oxidised to form oxygen.
Combustion forms the classic example of redox reactions in real-life. However, whenever we talk about combustion, we usually view it as a physical change than a chemical one. The burning of organic material and combustion of hydrocarbons in fossil fuels form yet another important example of redox reactions. The oxygen present in the atmosphere bonds with carbon and hydrogen present in the compound being burned. During the process of combustion, the oxygen present in the atmosphere is being reduced whereas the compound which is being burned is undergoing oxidation.
The process of photosynthesis takes place in the leaves of the plants. What happens is that carbon dioxide and water combine in the presence of sunlight to release oxygen and glucose. The glucose which is formed in the whole process of photosynthesis is used to fuel the metabolic reactions of the plants. In photosynthesis, water is oxidised and carbon dioxide is reduced.
The process of developing a photographic film also employs redox reactions. The silver ions in activated silver bromide are reduced to silver atoms by reducing chemicals like hydroquinone or pyrogallos. In addition, sodium thiosulfate is also used in the process of obtaining a negative. A positive image is obtained by the exposure of the negative to light. Following the exposure to light, silver cations are reduced.
A bleaching agent is a substance which has the ability to whiten or decolourize other substances. The process of bleaching also employs a number of redox reactions. Decolourization of a substance occurs because the electrons move between different energy levels. Any sort of decolourization can be removed by the oxidation of the electrons.
The process of corrosion forms yet another example of redox reactions in everyday life. On contact with a metal, say, an iron door, some of the oxygen atoms present in water oxidise iron (or the metal) and, thereby, lead to the generation of free hydrogen ions. The hydrogen ions generated combine with oxygen to yield water, and the whole cycle begins once again.
7. Breathalyzer/Breath Analyzers
Cops often use breathalyzers or breath analyzers to estimate the content of alcohol in a driver’s breath. Even the breathalyzers employ the chemical principle of redox reactions. Once a diver breathes into the breathalyzers, an acidic solution of potassium dichromate reacts with it. What happens is that the ethanol in the breath is oxidised to acetic acid; whereas the chromium (IV) in the orange-yellow dichromate ion is reduced to chromium(III) which is green in colour. The amount of colour change corresponds to levels of alcohol in the blood.
The redox reactions have widespread utilization in the field of medicine. Hydrogen peroxide, the most commonly used antiseptic, is responsible for liberating nascent oxygen; which, in turn, oxidizes necrotic matter and bacteria. Hydrogen peroxide helps in removal as well as the loosening of the slough, ear wax, etc. One of the widely used drugs for acne, i.e, benzoyl peroxide kills bacteria, especially anaerobic bacteria, by the liberation of oxygen in the presence of water.
The living matter in nature, primarily, is made up of carbon, hydrogen, and oxygen. Upon the death of any living organism, the organic compounds present in the organism start reacting with oxygen. The aforesaid reaction is a prolonged process. This process commonly referred to as “decay” or “decomposition” forms another example of redox reactions.