Redox in everyday life

rusting, photography, photosynthesis

1. The action of common oxidizing and reducing substances in everyday activities

2. The process of corrosion forms yet another example of redox reactions in everyday life. On contact with a metal, an iron and its alloy is exposed to oxygen atoms and moisture/water the iron (or the metal) is oxidized by the oxygen to form hydrated iron (III) oxide, Fe 2 O 3 and free hydrogen ions. The iron (III) oxide is known as RUST. The hydrogen ions generated combine with oxygen to yield water, and the whole cycle begins once again. Given enough time and exposure the iron will completely oxidise Corrosion/Rusting

3. Bleach 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 of the bleach containing sodium chlorate (I) ( NaClO ). Oxygen bleaches contain hydrogen peroxide (H 2 O 2 ) Both bleaches the coloured dye/stain to their colourless form ClO ⁻ ( aq ) + coloured dye Cl⁻ ( aq ) + colourless dye Hydrogen peroxide, is also commonly used as an antiseptic, is responsible for liberating oxygen; which, in turn, oxidizes necrotic matter and bacteria. Hydrogen peroxide helps in removal as well as the loosening of the slough, ear wax, acne etc.

4. The breathalyzer test 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 driver breathes into the breathalyzers sample of orange potassium chromate (VI) crystals (K2Cr 2 O 7 ), What happens is that the ethanol in the breath is oxidised , the dichromate orange-yellow ion ( Cr 2 O 7 ⁻ ) is reduced to chromium(III)( Cr ⁺ ) which is green in colour . The amount of colour change corresponds to levels of alcohol in the blood. Click mouse on white block and press the play icon to watch a short video or Right click on link to watch https :// www.youtube.com/watch?v=rvVzlg26bCM

5. Browning of Fruits Oxidation reactions occur in food and non-food items. Enzymic browning is a reaction which requires the action of enzymes and oxidation in order to occur.  What happens during enzymic browning?   Oxygen in the air can cause sliced fruit to brown, a process called enzymic browning (an oxidation reaction). Cells of the apple when exposed to oxygen in the air, for example through slicing, the oxygen causes a reaction.  Chemicals in the fruits cells change into melanin, which has a brown colourYou may have heard of melanin before.  Melanin is the pigment that gives human hair, skin and eyes their colour . Why does enzymic browning happen? Foods are made up of lots of different molecules including some called enzymes. Enzymes are special proteins which can speed up chemical reactions and act as biological catalysts. They can cause fruit to ripen and over-ripen, which gives the fruit a brown colour . Fresh fruit and vegetables normally keep enzymes trapped in their tissues.  However when the fruit is sliced, or squashed, or when the fruit or vegetable begins to break down with age, the enzymes come into contact with oxygen in the air. This causes the fruit to turn brown.

6. Food preservation Sodium sulfites and suphur dioxide are typically added to processed foods to prevent microbial spoilage and keep them from browning or changing color. They do this by preventing oxidation. They enhance flavor, preserve freshness, prevent spoilage and discolouration of foods such as wines, fruits, fruits juices, dried fruits, dried potatoes etc. The earliest known use of sulfites was in the treatment of wines with  sulfur dioxide  by the Romans. Sulfites are sprayed on fresh foods such as shrimp, fruits, and vegetables. They are also used as antioxidants and preservatives in many pharmaceuticals.

7. Respiration 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.

8. Combustion 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.

9. Photosynthesis 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.

10. Photography 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 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.

11. References https:// www.youtube.com/watch?v=rvVzlg26bCM https://studiousguy.com/examples-redox-reactions-everyday-life / Tindale, Ritchie et al, 2014, Chemistry for CSEC 2nd Edition , Nelson Thornes. Chapter 9, p156-157 https:// www.ifst.org/lovefoodlovescience/resources/fruit-and-vegetables-enzymic-browning