JEE Main2015ChemistryCoordination CompoundsActual
When concentrated HCl is added to aqueous solution of C o C l 2 , its colour changes from reddish pink to deep blue. Which complex ion gives blue colour in reaction?
Options
- AC o C l 6 4 -
- BC o C l 6 3 -
- CC o H 2 O 6 2 +
- DC o C l 4 2 -
Correct answer
D. C o C l 4 2 -
Step-by-step solution
On addition of conc. HCl . The equilibrium between two coloured Co (II) species can be described by equation Co H 2 O 6 aq 2 + + 4 Cl aq - ⇌ CoCl 4 aq 2 - + 6 H 2 O ℓ Pink Blue The equilibrium is disturbed by changing the conc. of C l - ions by addition of conc. HCl in forward direction.