After learning about endothermic reactions, it is obvious to know what is an exothermic reaction. In this article, we will discuss the definition of exothermic reaction and examples of exothermic reaction.
Define exothermic reaction
The chemical
reactions in which heat energy is liberated or given out are called exothermic reactions.
A
+ B → C + D + heat
In exothermic
reactions, the total amount of energy of reactants is greater than the total amount
of energy of products.
Energy
of reactants > energy of products
`C + O_2\rightarrow CO_2 + 395kJ`
`CH_4 + 2O_2\rightarrow CO_2 + H_2O + 890kJ`
Why heat is released in an exothermic reaction
During a chemical reaction, bonds in
reactants are broken down and new bonds are formed in the products.
In an exothermic reaction, reactants have
higher energy than products.
Energy is released when bonds in the reactants
are broken down, some amount of energy is used in the formation of new bonds in
the products and the remaining amount of energy is released.
Examples of exothermic reaction
Following are the examples of exothermic reaction
1. Addition of Calcium oxide in water: - When
calcium oxide is added to water, a huge amount of heat is liberated. The reaction
is exothermic.
`CaO + H_2O →Ca(OH)_2
+ heat`
2. Combustion
of natural gas: - Natural gas contains mainly methane. When methane burns in
oxygen or air, a large amount of heat energy is produced. So, this is an
exothermic reaction.
`CH_4 + O_2 → CO_2 +H_2O +heat`
3. Reaction
of a strong acid with water: - When a strong acid(sulphuric acid) is added to water,
it dissociates into ions and a large amount of heat is produced. This is an exothermic
reaction.
4. Decomposition
of organic waste material: - Organic waste material like peels of vegetables, and food items undergo decomposition by the action of microorganisms. This process
liberates heat, so this is an exothermic reaction.
5. Dissolution
of washing powder in water:- When washing powder is added to water, the temperature
of the water increases due to the liberation of heat. This is an exothermic reaction.
Quiz for you
Related Topics
1. What happens during a chemical reaction
FAQs
1. What is an example of an exothermic reaction?
Ans.- Burning of wood or coal.
2. What happens in an exothermic reaction?
Ans. - Energy in the form of heat is released in an exothermic reaction.
3. What is a real-life example of an exothermic reaction?
Ans - Burning of fuel in combustion engines.
4. Which result occurs during an exothermic reaction?
Ans. - Releasing of heat occurs during an exothermic reaction.
5. Which has greater energy in an exothermic reaction, the reactants or the products?
Ans. - Energy of reactants > energy of products, reactant has more energy in an exothermic reaction.
6. What is calcium chloride and water exothermic reaction?
Ans.- `CaCl_2 + 2H_2O → Ca(OH)_2 + 2HCl`
7. For an exothermic reaction at equilibrium, what will happen if the temperature is increased?
Ans. The equilibrium will shift towards the reactant side if the temperature is increased in an exothermic reaction at equilibrium.
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