18.7 The Co2+/ Co(SCN)42- Equilibrium

Chemical Concept Demonstrated:  The tendency for ionic substrates to extract into more polar solvents


75 mL of water are poured into a funnel.

A blue ether solution, made up of KSCN, CoCl2, and ethyl ether, is added to the funnel.

The funnel is stoppered and the contents inside are shaken.


    The water layer changes into a pink solution at the bottom of the separatory funnel.


    Water is more polar than ethyl ether.  Some of the Co2+ ions are extracted into the water layer from the Co(SCN)4 2- complex ions formed in the ether solution.  The presence of Cl - can be seen by adding silver nitrate (AgNO3) solution until a white precipitate forms in the water layer at the bottom of the separatory funnel.