# Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity

## What is decomposition reaction?

A decomposition reaction occurs when a compound breaks down into two or more simpler substances. Energy is required for most decomposition reactions, either through heat, light, or electricity.

(a) Thermal decomposition reaction (Thermolysis)

Thermal decomposition occurs when a substance is broken down by heat into two or more other substances.

Decomposition of potassium chlorate: When heated strongly, potassium chlorate decomposes into potassium chloride and oxygen. This reaction is used for the preparation of oxygen.

2KClO3 + Heat → 2KCl + 3O2

(b) Electrolytic decomposition reaction (Electrolysis)

An electrolysis decomposition occurs when a substance is broken down into two or more substances using electricity.

Decomposition of sodium chloride: On passing electricity through molten sodium chloride, it decomposes into sodium and chlorine.

2NaCl2 → Na + Cl2

(c) Photodecomposition reaction (Photolysis)

A photolytic reaction occurs when a substance breaks down or decomposes into two or more substances.

Decomposition of hydrogen peroxide: In the presence of light, hydrogen peroxide decomposes into water and oxygen.

2H2O2 → 2H2O + O2

## Explain double displacement reaction with an example.

Double displacement reactions occur when ions of the reactants exchange places to form two new compounds.

The two reactants that participate in double displacement reactions are generally water-soluble, with one product being soluble and the other being insoluble.

The reaction between sodium hydroxide and hydrochloric acid produces sodium chloride and water.

NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)

## What do you mean by Combination reactions?

Combination reactions occur when two or more substances combine to form a new substance.

Example: When iron and sulphur are heated together, they combine to form a single product, iron sulphide.

2Fe (Iron) + S (Sulphur) → FeS (Iron sulphide)