Here's the breakdown of the reaction:
1. Initial Reaction: Ammonia (NH₃) reacts with copper(II) hydroxide (Cu(OH)₂) to form a deep blue solution. This reaction is an equilibrium reaction, meaning it can proceed in both directions.
Cu(OH)₂(s) + 4NH₃(aq) ⇌ [Cu(NH₃)₄]²⁺(aq) + 2OH⁻(aq)
2. Formation of the Complex Ion: The copper(II) ion (Cu²⁺) in solution acts as a Lewis acid, accepting electron pairs from the ammonia molecules. Ammonia acts as a Lewis base, donating electron pairs. This results in the formation of the tetraamminecopper(II) complex ion, [Cu(NH₃)₄]²⁺. The four ammonia molecules coordinate to the central copper(II) ion, forming a coordination complex.
The deep blue color of the solution is characteristic of the tetraamminecopper(II) complex ion.
