Question

Cu2+ forms a deep blue solution with aqueous ammonia

Answer 1

When concentrated ammonia solution (ammonium hydroxide) is added to a clear, light blue, aqueous solution of copper(II) chloride, a powdery, light blue precipitate of copper(II) hydroxide forms. Further addition of ammonia causes the copper ion to go back into solution as a deep blue ammonia complex.

Answer 2

When Ammonium Hydroxide solution is added to copper solution a blue precipitate of Copper Hydroxide is formed.

this is when Ammonium Hydroxide is added in small amounts.

When we continue to add more drops of Ammonium hydroxide solution the blue precipitate dissolves to form a deep blue solution.

This deep blue solution is a complex copper ion with Ammonia.

The deep blue solution is thus formed due to the complex ion of copper and ammonia formed.