Question

Decomposition Reactions require energy in the form of heat or light or electricity for breaking down the reactants. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light and electricity.

Answer 1

Hint: Decomposition reactions need the energy to break down the stable molecules into their subsequent simpler products. This energy can be termed as Initiation Energy.

Complete step by step solution:
A decomposition reaction can be defined as a chemical reaction in which one reactant breaks down into two or more products. Now, it will break because we are providing energy in any form to break down the reactant.
To break a stable molecule to undergo decomposition reaction, it must be given energy from external sources like heat, light or electricity.
This initiation of energy increases the kinetic energy between the molecules so that they can be broken into simpler products.
A thermal decomposition reaction can be defined as a decomposition reaction which is activated by thermal energy. In other words, a thermal decomposition reaction requires energy to be supplied to the reactants in the form of heat. Such reactions are generally endothermic since energy is required to break the chemical bonds and separate the constituent elements. A common example of a thermal decomposition reaction is provided below.
$$\mathrm{CaCO}_{3} \rightarrow \mathrm{CaO}+\mathrm{CO}_{2}$$
An electrolytic decomposition reaction is a type of decomposition reaction in which the activation energy for decomposition is provided in the form of electrical energy. An example of an electrolytic decomposition reaction is the electrolysis of water, which can be represented by the following chemical equation:
$$2 \mathrm{H}_{2} \mathrm{O} \rightarrow 2 \mathrm{H}_{2}+\mathrm{O}_{2}$$
A photodecomposition reaction is a type of decomposition reaction in which the reactant is broken down to its constituents by absorbing energy from photons. An example of a photo-decomposition reaction is the decomposition into dioxygen and an oxygen radical, as represented by the chemical equation provided below.:
$$2 \mathrm{HBr} \rightarrow \mathrm{H}_{2}+\mathrm{Br}_{2}$$

Additional information:
When heated, calcium carbonate decomposes into calcium oxide and carbon dioxide. This process is employed in the manufacturing of quick lime, which is an important substance in many industries.
Uses of Decomposition Reactions
-Manufacture of cement or calcium oxide.
-For metallurgical processes: Extraction of metals from their oxides, chlorides, etc.
-The relief from acid indigestion.
-Thermite welding.

Note: Decomposition reaction should need the initiation energy. Without the external energy in any form, it is not possible for the reactant to break down.