Chemistry

Examples of chemical changes

We explain that what are examples of chemical changes? A chemical change is the difference between the initial and final states of a material when its chemical structure has been altered , that is, the arrangement and type of its atoms or molecules. This is because the links that form it are configured differently. Therefore, when a chemical change occurs, there will be a modification at both a microscopic and macroscopic level of the matter in question.

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It also happens that their properties, both physical and chemical , end up being different. It can be seen by its new appearance. During this transformation, an energy exchange takes place between the substance and its surroundings. Whether it is emitted or absorbed in the system, it will be the amount that corresponds to the chemical change and that will lead to a new equilibrium .

Although chemical change is the comparison between the beginning and the actuality of a substance, the process that is carried out to achieve it is the chemical reaction , which is represented graphically by means of an equation. An equation contains the formulas for both reactants and products, and describes which species interact and which are formed.

To illustrate, a chemical equation has the following format:

A + B -> C + D

Where A and B are the reactants , that is, the original substances that go into reaction to generate C and D, which are the products , new substances that contain the rearranged atoms of the reactants.

Generally, chemical changes are irreversible or permanent. However, there are some substances that, being isolated in a closed system, such as a reactor, can behave in such a way that the products generate reagents back, thus giving the reverse reaction and promoting reversibility.

Types of chemical changes

Depending on their nature and type of action, chemical changes will be of three types:

  • Inorganic
  • Organic
  • Biological

Inorganic chemical changes are those in which inorganic substances are involved, such as: metals, non-metals, metalloids, oxides, hydroxides, hydracids, oxacids, salts, oxysalts.

Organic chemical changes are those in which organic compounds are involved, such as hydrocarbons, alcohols, aldehydes, ketones, carboxylic acids, ethers, esters, mercaptans, amines, amides.

Biological chemical changes are those in which biochemical compounds are involved, such as carbohydrates, lipids, amino acids, proteins, enzymes, vitamins, and that provide a nutritional factor for the functioning of cells.

60 examples of chemical changes

20 examples of inorganic chemical changes

  1. The oxidation of iron, which is produced by the incidence of humidity and oxygen in the air. From Fe it is converted to FeO or Fe 2 O 3 . From a dark gray color it turns orange-red.
  2. The oxidation of copper, which occurs when moisture and oxygen in the air act. From Cu it is converted to Cu 2 O or CuO. From a reddish-gold color it turns to bluish green.
  3. The oxidation of silver, which occurs slowly when moisture and oxygen in the air act. From Ag becomes AgO. From its bright gray color it turns to a dark gray.
  4. The oxidation of calcium, due to the action of oxygen in the air. From Ca to CaO. From a whitish gray color it turns to white.
  5. The oxidation of zinc, by the action of oxygen in the air. From Zn to ZnO. From a light and opaque gray color it turns to dark red.
  6. Neutralization of hydrochloric acid HCl with sodium hydroxide NaOH. They affect each other and produce sodium chloride NaCl and water H 2
  7. Neutralization of hydrobromic acid HBr with sodium hydroxide NaOH. They affect each other and produce sodium bromide NaBr and water H 2
  8. Neutralization of hydroiodic acid HI with sodium hydroxide NaOH. They affect each other and produce sodium iodide NaI and water H 2
  9. Neutralization of hydrochloric acid HCl with potassium hydroxide KOH. They affect each other and produce potassium chloride KCl and water H 2
  10. Neutralization of hydrobromic acid HBr with potassium hydroxide KOH. They affect each other and produce KBr potassium bromide and H 2 water
  11. Neutralization of hydroiodic acid HI with potassium hydroxide KOH. They affect each other and produce potassium iodide KI and water H 2
  12. Neutralization of sulfuric acid H 2 SO 4 with sodium hydroxide NaOH. They counteract and produce sodium sulfate Na 2 SO 4 and water H 2
  13. Neutralization of sulfuric acid H 2 SO 4 with potassium hydroxide KOH. They counteract and produce potassium sulfate K 2 SO 4 and water H 2
  14. Neutralization of sulfuric acid H 2 SO 4 with calcium hydroxide Ca (OH) 2 . They counteract and produce calcium sulfate CaSO 4 and water H 2
  15. Neutralization of sulfuric acid H 2 SO 4 with magnesium hydroxide Mg (OH) 2 . They counteract and produce magnesium sulfate MgSO 4 and water H 2
  16. The neutralization of sulfuric acid H 2 SO 4 with aluminum hydroxide Al (OH) 3 . They counteract and produce aluminum sulfate Al 2 (SO 4 ) 3 and water H 2
  17. Neutralization of phosphoric acid H 3 PO 4 with sodium hydroxide NaOH. They counteract and produce sodium phosphate Na 3 PO 4 and water H 2
  18. The production of ammonia NH 3 from nitrogen (N) and hydrogen (H).
  19. Obtaining sulfur trioxide SO 3 from sulfur dioxide SO 2 and oxygen O 2 at high temperatures.
  20. Obtaining zinc chloride ZnCl 2 from hydrochloric acid HCl and zinc Zn shot.

20 examples of organic chemical changes

  1. The combustion of wood, whose cellulose is decomposing into carbon dioxide CO 2 and water vapor H 2 O, emitting a lot of heat.
  2. The combustion of methane gas CH 4 , whose molecules are decomposing into carbon dioxide CO 2 and water vapor H 2 O, emitting a lot of heat.
  3. The combustion of acetylene gas C 2 H 2 , whose molecules decompose into carbon dioxide CO 2 and water vapor H 2 O, emitting a lot of heat.
  4. The combustion of ethane gas C 2 H 6 , whose molecules decompose into carbon dioxide CO 2 and water vapor H 2 O, emitting a lot of heat.
  5. The combustion of propane gas C 3 H 8 , whose molecules are decomposing into carbon dioxide CO 2 and water vapor H 2 O, emitting a lot of heat.
  6. The combustion of butane gas C 4 H 10 , whose molecules are decomposing into carbon dioxide CO 2 and water vapor H 2 O, emitting a lot of heat.
  7. The combustion of pentane gas C 5 H 12 , whose molecules are decomposing into carbon dioxide CO 2 and water vapor H 2 O, emitting a lot of heat.
  8. The combustion of hexane gas C 6 H 14 , whose molecules are decomposing into carbon dioxide CO 2 and water vapor H 2 O, emitting a lot of heat.
  9. The combustion of LP gas, which is a mixture of C 3 H 8 propane and C 4 H 10 butane, the molecules of which decompose into carbon dioxide CO 2 and water vapor H 2 O, emitting a lot of heat.
  10. The combustion of octane C 8 H 18 , whose molecules are decomposing into carbon dioxide CO 2 and water vapor H 2 O, emitting a lot of heat.
  11. The formation of sodium acetate CH 3 COONa by neutralizing acetic acid CH 3 COOH with sodium hydroxide NaOH.
  12. The formation of sodium propionate CH 3 CH 2 COONa by neutralizing propionic acid CH 3 CH 2 COOH with sodium hydroxide NaOH.
  13. The formation of sodium butyrate CH 3 CH 2 CH 2 COONa by neutralizing butyric acid CH 3 CH 2 CH 2 COOH with sodium hydroxide NaOH.
  14. Commercial soap making uses the reaction of formation of sodium stearate CH 3 (CH 2 ) 16 COONa by neutralizing stearic acid CH 3 (CH 2 ) 16 COOH with sodium hydroxide NaOH.
  15. The formation of ethyl acetate CH 3 COOC 2 H 5 by the union of the molecules of acetic acid CH 3 COOH and of ethyl alcohol C 2 H 5
  16. The formation of propyl acetate CH 3 COOC 3 H 7 by the union of the molecules of acetic acid CH 3 COOH and of propyl alcohol C 3 H 7
  17. The formation of butyl acetate CH 3 COOC 4 H 10 by the union of the molecules of acetic acid CH 3 COOH and of butyl alcohol C 2 H 5
  18. The formation of acetyl acetate CH 3 COO (OCCH 3 ) by the union of two molecules of acetic acid CH 3
  19. The formation of propanoyl acetate CH 3 COO (OCCH 2 CH 3 ) by the union of the molecules of acetic acid CH 3 COOH and propionic acid CH 3 CH 2
  20. When vinegar, which contains acetic acid CH 3 COOH, and a little sodium bicarbonate NaHCO 3 are combined, an effervescence occurs, that is, carbon dioxide is released.

20 examples of biological chemical changes

  1. The metabolism of lipids.
  2. The degradation of starch thanks to the enzyme amylase.
  3. The assimilation of gluten by the tissue transglutaminase enzyme.
  4. Photosynthesis takes carbon dioxide CO 2 from the environment and sunlight to produce glucose C 6 H 12 O 6 that feeds plants.
  5. During fermentation, yeasts, which are microscopic fungi, break down complex carbohydrates to alcohols and carbon dioxide CO 2 .
  6. Mitochondria in cells produce adenosine triphosphate (ATP) molecules, which is the quintessential energy molecule.
  7. An electrochemical battery or cell is made up of aqueous sulfuric acid and two electrodes. There are ions circulating that allow the passage of electric current.
  8. During respiration, the pigment hemoglobin picks up inhaled oxygen in the lungs and combines with it to produce oxyhemoglobin.
  9. To terminate respiration, the cells expel carbon dioxide, which will be transported by hemoglobin to the lungs for disposal.
  10. During the frying process, the oil that is made up of unsaturated carboxylic acids takes hydrogen from the food molecules immersed in it.
  11. The oxidation of DNA helices by the action of free radicals.
  12. Food is broken down by gastric acid, which contains hydrochloric acid.
  13. Amino acids join in long chains to form polymers called proteins.
  14. Proteins are organized in tissues to form muscles and skin.
  15. Carbohydrates are assimilated thanks to enzymes, which are involved in metabolism.
  16. Soil bacteria are responsible for assimilating the nitrogen that comes from biological waste to nourish the earth.
  17. Prehistoric organisms have settled on the ground and decomposed under high pressure to become oil.
  18. Fermentation of lactose in milk to lactic acid, which forms yogurt.
  19. When an antibiotic medicine is used, its active agent attacks the membranes of pathogenic bacteria.
  20. Saprophytic bacteria feed by breaking down dead matter to simpler biochemical compounds. This applies to biological water treatment.

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