A chemical reaction occurs when one or more compounds combine or transform into completely different compounds.
Chemical reactions are everywhere, not only in specialized industrial laboratories, but also in the kitchen, in the environment, and in the body.
Below we show you examples of chemical reactions that you will be able to recognize in your daily life.
1. Combustion reaction of cooking gas
Propane C3H8 is an organic compound that reacts with oxygen O2 in the air to produce carbon dioxide CO2, water vapor H2O, and the energy used to heat food.
2. Oxidation-reduction reaction of car batteries
Car batteries are made of lead oxide PbO2 and sulfuric acid H2SO4. These react giving rise to an electrical current necessary to start the car.
The reaction that occurs results in lead sulfate PbSO4 and water:
3. Neutralization reaction of stomach acid with antacids
Stomach acid is hydrochloric acid HCl. Some antacids contain magnesium hydroxide Mg(OH)2. In the stomach, hydrochloric acid is neutralized with magnesium hydroxide to produce magnesium chloride and water in an acid-base reaction:
4. Reaction of vinegar and eggshell
Vinegar is a solution of acetic acid CH3COOH, which is a weak organic acid. The eggshell is made of calcium carbonate CaCO3. When we place an egg in vinegar, we can observe the appearance of some bubbles (carbon dioxide) and after a while the shell loses its rigidity.
The reaction that occurs between calcium carbonate and acetic acid produces calcium acetate CH3COOCa and carbon dioxide CO2:
5. Combustion of ethanol
Ethyl alcohol or ethanol can be used as fuel. In countries like the United States and Brazil, fossil fuels are being replaced by ethanol, as part of measures to reduce greenhouse gases. The reaction that occurs is:
6. Reaction of hydrogen peroxide in wounds
When we have a wound and we apply hydrogen peroxide, we almost immediately observe the appearance of bubbles. This occurs because in our blood cells we have an enzyme called catalase, which speeds up the breakdown reaction of hydrogen peroxide into water and oxygen:
7. Addition reactions for LEGO
A polymer is a substance made up of many smaller molecules joined together. These are produced by addition reactions. For example, the polymer acrylonitrile-butadiene-styrene, or ABS, is the substance from which LEGO bricks are built, as well as 3D printed products.
The reaction occurs between styrene, butadiene, and acrylonitrile:
8. Ozone formation reaction
Ozone O3 is a compound that is abundant in the stratosphere, one of the layers of the Earth’s atmosphere. This compound prevents the entry of harmful ultraviolet rays from the sun.
Ozone results from the combination of molecular oxygen O2 and elemental oxygen:
9. Milk sugar degradation reaction
Milk contains a sugar, lactose, made up of galactose and glucose. Human beings have an enzyme, lactase, which is responsible for accelerating the chemical reaction of lactose breakdown as follows:
Some people lose this enzyme when they become adults, so they no longer have the ability to digest milk.
10. Neutralization reaction
Sodium bicarbonate NaHCO3 is a weak base that when reacted with hydrochloric acid HCl produces sodium chloride salt NaCl, carbon dioxide CO2 and water H2O:
For this reason, when we drink water with bicarbonate of soda, we can feel stomach discomfort due to the gas that is produced in this reaction.
11. Esterification reaction
Esters are organic compounds with fruity odors. In manufactured food products these compounds are used for flavoring. It is much cheaper to chemically produce esters than to extract them from the fruits that produce them.
For example, the smell of banana is due to pentylethaneate. This ester is produced from the reaction of ethanoic acid and pentanol, in the presence of sulfuric acid as a catalyst:
12. Baking powder reaction
Baking powder and self-rising flour contain among their ingredients tartaric acid COOH(CHOH)2COOH and sodium bicarbonate NaHCO3. When the temperature is increased when baking or cooking a recipe with these compounds, the reaction occurs with the release of carbon dioxide, which causes the cakes to puff up:
13. Ocean acidification reaction
Carbon dioxide CO2 from the atmosphere dissolves in ocean water and can react to form carbonic acid:
This reaction is responsible for the decrease in the pH of the oceans, which implies alterations in the marine ecosystem.
14. Iron corrosion reaction
Corrosion of iron-bearing materials is accelerated in humid conditions. Iron and oxygen from the air react in the presence of water in an oxidation-reduction type reaction. The oxide that forms is hydrated iron oxide Fe2O3.H2O:
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References
Commons, C., Commons, P (editors) (2020). Heinemann Chemistry 1, 5th ed. Pearson Australia. Melbourne.
Moore, JT (2011) Chemistry for Dummies 2nd ed. Wiley Publishing. Indiana.