* Ammonia (NH₃) reacts with water (H₂O) to form ammonium ions (NH₄⁺) and hydroxide ions (OH⁻):
NH₃ + H₂O ⇌ NH₄⁺ + OH⁻
* Hydroxide ions (OH⁻) are responsible for alkalinity. The presence of these ions makes the solution basic, also known as alkaline.
* The equilibrium of this reaction lies slightly towards the formation of hydroxide ions. This means there are more OH⁻ ions than H⁺ ions in the solution, resulting in a pH greater than 7.
Therefore, an aqueous solution of ammonia is considered alkaline due to the presence of hydroxide ions.
