The aqueous solution of transition metal salt changes colour from pink to blue
CHEMISTRY · Single correct · A Level · Chemistry · Transition metals and their chemistry · Transition metals and their chemistry
Problem
The aqueous solution of transition metal salt changes colour from pink to blue, when concentrated hydrochloric acid is added to it. The change in colour is due to :
(1) evolution of hydrogen that changes the oxidation state of the metal ion
(2) change in the coordination number of the metal ion from 6 to 4 and formation of new species in solution
(3) formation of a coordination complex of the metal ion with hydrochloric acid
(4) protonation of the metal ion