Chemical reactions are the series of processes in which compounds, mixtures and elements which are called the reactants undergo to form new products.
Types of Chemical Reactions
One of the ways in which chemical reactions can be identified and grouped is according to their features and the nature of changes undergone by the chemical reactants.
Listed below are some types of chemical reactions according to their features and nature of changes they undergo.
Combination Reactions (Synthesis):
Combination reaction which is also known as synthesis, involves the merging of two or more chemical reactants to form a new product.
Example: C + D → CD
Decomposition reactions involve the disintegration of a chemical substance into smaller and less complex substances or elements.
Example: CD → C + D
Displacement Reactions (Single and Double):
Displacement reactions are classified into two, single displacement reactions and double displacement reactions. Single displacement involves the disposition of an element in a compound by another element. In double displacement, two chemical compounds interchange ions.
Example of Single displacement: A+ DC→ AD + C
Example of Double displacement: AD+ CB → AC+ BD
Oxidation-Reduction Reaction (Redox):
Oxidation - Reduction reaction also known as Redox reaction that involves two reactants known as an oxidizing agent and a reducing agent. In this reaction, electrons are gained by the oxidizing agent and lost by the reducing agent.
2Mg + O2 → 2MgO
In the example above, Mg is Oxidized while O2 is Reduced.
Combustion reaction is a type of reaction where Oxygen reacts with an element or substance to release energy in the form of heat and light.
CH4 + 2O2 → CO2 + 2H2O
Neutralization Reactions also called Acid-base reactions are reactions between an Acid and a base. In this type of reaction, H⁺ ions are transmitted from the Acid to the base. The product of this type of reaction is salt and water.
An example of this reaction is when Hydrochloric acid reacts with Sodium Hydroxide to produce salt (sodium chloride) and Water.
HCl + NaOH → H2O + NaCl
When two chemical substances react to give an insoluble substance as a by-product, they do so through a process called Precipitation reaction.
The insoluble substance is called a precipitate.
Example: AgNO3 + NaCl → AgCl + NaNO3
Photochemical reactions are reactions that occur under the presence of light, in this type of reaction, when light energy is absorbed by a chemical substance, it leads to either the breakdown or formation of chemical bonds which form new products.
An example of photochemical reactions is Photosynthesis which occurs in plants.
Thermal Decomposition Reactions:
When Heat is absorbed by a Chemical compound to break down into less complex compounds or substances, it is called a Thermal Decomposition reaction.
Example: CaCO3 (s) → CaO (s) + CO2 (g)
Endothermic and Exothermic Reactions:
An Endothermic reaction is one in which heat is absorbed from the environment during the reaction while an Exothermic reaction is one in which heat is expended into the environment during the reaction.
Example of Endothermic reaction:
NH4NO3 (s) → NH4⁺ (aq) + NO3⁻ (aq) (cold pack reactions)
Example of Exothermic reaction:
CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (g) (combustion of methane)
The study of how different molecules and substances react with each other has so far remained very crucial in the field of Chemistry.
Through the knowledge obtained from the study of Chemical reactions, Scientists have been able to make new innovations and make new discoveries.
Written so far in this article are some basic ways in which substances react with each other chemically. Our world is one filled with different atoms, molecules and compounds. Understanding and predicting how they react with each other is the key to shaping our world and making lives better.
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