When aqueous ammonia is added in excess to a silver chloride solution, the following observations can be made:

1. Initially, a white precipitate of silver chloride forms due to the reaction between silver ions (Ag+) from the silver chloride solution and chloride ions (Cl-) from the aqueous ammonia.

2. As more ammonia is added, the silver chloride precipitate dissolves and forms a complex ion called diamminesilver(I) ion ([Ag(NH3)2]+). This complex ion is soluble in water.

3. The solution becomes colorless as the silver chloride precipitate dissolves.

The overall reaction can be represented as:

AgCl(s) + 2 NH3(aq) -> [Ag(NH3)2]+(aq) + Cl-(aq)

This reaction is reversible, and the addition of excess ammonia drives the equilibrium towards the formation of the complex ion.