* Ammonia is a base: Ammonia (NH₃) is a weak base. This means it produces hydroxide ions (OH⁻) when dissolved in water.
* Litmus paper as an indicator: Litmus paper is a natural dye that acts as a pH indicator. It changes color depending on the acidity or alkalinity of a solution.
* Red litmus paper indicates acid: Red litmus paper is acidic and will remain red in acidic solutions.
* Blue litmus paper indicates base: Blue litmus paper is basic and will remain blue in basic solutions.
* The reaction: When ammonia dissolves in water, it reacts to produce hydroxide ions (OH⁻):
NH₃(aq) + H₂O(l) ⇌ NH₄⁺(aq) + OH⁻(aq)
* Color change: The presence of hydroxide ions (OH⁻) makes the solution basic. This basic solution then turns the red litmus paper blue, indicating the presence of a base.
In summary: The solution of ammonia turns red litmus paper blue because ammonia is a base and the hydroxide ions it produces in solution change the pH of the solution, making it alkaline.
