When ammonia (NH₃) dissolves in water, it produces ammonium hydroxide (NH₄OH). This is a weak base that exists in equilibrium with ammonia and water molecules:

NH₃(g) + H₂O(l) ⇌ NH₄⁺(aq) + OH⁻(aq)

Here's what happens:

* Ammonia molecules (NH₃) react with water molecules (H₂O) to form ammonium ions (NH₄⁺) and hydroxide ions (OH⁻).

* The ammonium ion is a weak acid, and the hydroxide ion is a strong base.

* The equilibrium lies heavily towards the reactants (ammonia and water) meaning that most of the ammonia remains in solution as NH₃.

The presence of hydroxide ions in solution makes ammonium hydroxide a weak base. This means that it can accept protons (H⁺) from acids to form the ammonium ion.

Note: The term "ammonium hydroxide" is often used to describe the solution, but technically, the species present in solution are ammonia molecules and a small amount of ammonium and hydroxide ions.