8 types of chemical reactions with examples

The main types of chemical reactions are:

  1. Acid-base reactions
  2. Oxidation-reduction reactions
  3. Combustion reactions
  4. Displacement reactions
  5. Double displacement reactions
  6. Acid-metal reactions
  7. Combination reactions
  8. Decomposition reactions

A chemical reaction is the process of arranging atoms between substances to form new compounds with different properties. In other words, when compounds or elements react, they are transformed into one or more different substances.

For example, when paper is burned, the oxygen in the air and the cellulose in the paper react and turn into carbon dioxide and water vapor.

The substances that react are called reactants and the substances that are generated are called products. A chemical reaction is represented by a chemical equation, where the reactants are placed to the left of an arrow followed by the products to the right, like this:

Reactants→Products

A nuclear reaction is not a chemical reaction, as it involves the transformation of atoms into another type of atom. For example, in the fission of uranium, krypton and barium are formed, while mass is lost in the form of energy. Nor are chemical reactions the dissolution of a substance in water or the ionization of a compound, as well as the change of state of a material.

Below we present the main types of chemical reactions with examples.

1. Acid-base reactions

Also called neutralization reactions, the reaction of an acid with a base occurs. The acid contributes H ions+ and the base contributes OH ions to form water H2Or, at the same time a salt is formed.

For example, when hydrochloric acid HCl reacts with sodium hydroxide NaOH, the products are H water2Or the sodium chloride salt NaCl:

bold HCl bold space bold plus bold space bold NaOH bold right arrow bold NaCl bold space bold plus bold space bold H subscript bold 2 bold O

You may also be interested in seeing Acids and bases.

2. Oxidation-reduction reactions

They are a type of chemical reaction where the reactants gain or give up electrons to each other. When they gain electrons they are reduced, when they lose electrons they are oxidized. Oxidation and reduction reactions are simultaneous.

For example, for the extraction of iron in mines, iron oxide III Fe2O3 is reduced by the action of carbon monoxide CO which oxidises. The products are iron in the elemental form Fe and carbon dioxide CO2:

style size 16px bold Fe subscript bold 2 bold O subscript bold 3 bold plus bold space bold 3 bold CO bold space bold right arrow bold 2 bold Fe bold space bold plus bold space bold 3 bold CO subscript black

You may also be interested in seeing Oxidation and Reduction.

3. Combustion reactions

In combustion reactions, oxygen combines with organic compounds, made up of carbon, hydrogen and oxygen. The end product is carbon dioxide and water.

An example of a combustion reaction is the one that occurs when methane CH is burned4 or cooking gas:

bold CH subscript bold 4 open parenthesis bold g close parenthesis end subscript bold plus bold 2 bold O subscript bold 2 open parenthesis bold g close parenthesis end bold subscript right arrow bold subscript bold H subscript bold 2 bold O subscript open parenthesis bold g close parenthesis end subscript

You may also be interested in seeing Organic and Inorganic Compounds.

4. Displacement reactions

In this type of reaction, one element replaces another in a compound. This is the case for the reaction between sodium Na and zinc iodide ZnI2where sodium displaces zinc to form sodium iodide NaI:

style size 16px bold 2 bold Na bold space bold more bold space bold ZnI subscript bold 2 bold right arrow bold 2 bold NaI bold space bold more bold space bold Zn fine style

5. Double displacement reactions

This reaction occurs in solution when the reactants are ionized, so ion exchange occurs. If the combination produces a compound that precipitates by forming an insoluble salt, we have a precipitation reaction.

For example, when reacting the salts barium nitrate Ba(NO3)2 and potassium sulfate K2SO4ions are exchanged to produce potassium nitrate KNO3 and barium sulfate BaSO4 which is insoluble in water and precipitates:

bold Ba bold left parenthesis bold NO subscript bold 3 bold right parenthesis subscript bold 2 bold space bold plus bold space bold K subscript bold 2 bold SO subscript bold 4 bold right arrow bold 2 bold subscript bold 4

6. Acid-metal reactions

An acid such as hydrochloric acid HCl and a metal can react to form a salt and hydrogen gas H2:

bold 2 bold HCl bold space bold plus bold space bold 2 bold Na bold right arrow bold 2 bold NaCl bold space bold plus bold space bold H subscript bold 2

7. Combination reactions

Elements or compounds are combined to form a different product. For example, sulfur dioxide SO2 combines with oxygen O2 to form sulfur trioxide SO3:

bold 2 bold OS subscript bold 2 bold space bold plus bold space bold O subscript bold 2 bold right arrow bold 2 bold OS subscript bold 3

8. Decomposition reactions

A simple compound gives rise to two or more products. An example of decomposition is the process of electrolysis, that is to say, when passing an electric current through water, it decomposes into hydrogen gas H2 and oxygen:

bold 2 bold H subscript bold 2 bold O bold right arrow with bold electricity above bold 2 bold H subscript bold 2 bold plus bold space bold O subscript bold 2

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References

Ahtee, M., Varjola, I. (2007) Students’ understanding of chemical reaction. International Journal of Science Education. 20: 305-316. DOI:10.1080/0950069980200304

Commons, C., Commons, P (editors) (2020). Heinemann Chemistry 1, 5th ed. Pearson Australia. Melbourne.

Rosenberg, JL, Epstein, LM, Krieger, PJ (2007) Schaum’s outlines College Chemistry 9th ed. McGraw-Hill. Toronto.

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