Question

Give one example each of electrolytic decomposition and decomposition by sunlight.

Hint:

Silver bromide (\( AgBr \)) also decomposes in sunlight and is used in black and white photography.

Answer 1

Decomposition Reactions:

A decomposition reaction is a chemical reaction in which a single compound breaks down into two or more simpler substances. This decomposition can take place due to electricity, heat, or sunlight.

1. Example of Electrolytic Decomposition:
Electrolytic decomposition occurs when electricity is passed through a compound in molten or aqueous state, causing it to break down into simpler substances. A common example is the decomposition of water: \[ 2H_2O (l) \xrightarrow{\text{electricity}} 2H_2 (g) + O_2 (g) \] In this reaction: – Water decomposes into hydrogen gas and oxygen gas.
– Electricity is required to bring about the reaction.

2. Example of Decomposition by Sunlight (Photochemical Decomposition):
Some compounds decompose when exposed to sunlight. A common example is the decomposition of silver chloride: \[ 2AgCl (s) \xrightarrow{\text{sunlight}} 2Ag (s) + Cl_2 (g) \] In this reaction: – White silver chloride turns grey due to the formation of silver.
– Sunlight provides the energy required for decomposition.

Final Answer: Electrolytic decomposition example: \[ \boxed{2H_2O \xrightarrow{\text{electricity}} 2H_2 + O_2} \] Decomposition by sunlight example: \[ \boxed{2AgCl \xrightarrow{\text{sunlight}} 2Ag + Cl_2} \]