Question

How does ammonia react with $C{u}^{2+}$ solution?

Answer 1

Ammonia acts as a Lewis base due to the presence of lone pair of electrons on the nitrogen atom.Therefore,it can form coordinate bond with electron deficient molecules or a number of transition metal cations to from complex compounds.Ammonia reacts with a solution of $C{u}^{2+}$ to form a deep blue coloured complex.The reaction for the above complex can be written as follows:

$C{u}_{\left(aq\right)}^{2+}+4N{H}_3\left(aq\right)\iff \left[Cu\right(N{H}_3{)}_4{]}^{2+}\left(aq\right)$

Blue Deep Blue

This property of ammonia to form complex compounds is useful in detection of metal ions.