When Ethane-1,2-diamine is added progressively to an aqueous solution of Nickel (II) chloride, the sequence of colour ch…

\(\text{ Reaction and colour changes }\\ {\left[\underset{\text{ Gren }}{Ni{\left({H}_{2}O\right)}_{6}}\right]}^{2+}(aq)+en(aq)\to {\left[Ni{\left({H}_{2}O\right)}_{4}(en)\right]}^{2+}(aq)+2{H}_{2}O\\ {\left[Ni{\left({H}_{2}O\right)}_{4}(en)\right]}^{2+}(aq)+en(aq)\to \left[\underset{\text{ Bluc/Purple }}{{\left.Ni{\left({H}_{2}O\right)}_{2}(en{)}_{2}\right]}^{2+}(aq)+2{H}_{2}O}\right.\\ \left[\underset{\text{ Bluc/Purple }}{{\left.Ni{\left({H}_{2}O\right)}_{2}(en{)}_{2}\right]}^{2+}(aq)+en(aq)\to }\right.\underset{\text{ violet }}{{\left.Ni(en{)}_{3}\right]}^{2+}}(aq)+2{H}_{2}O\)