Question

4. When CoCl2 is dissolved in water, the resulting solution is pink because of the presence of only) octahedrally coordinated [CoCI(H20)s] coordination complexes. If concentrated hydrochloric acid (a source of Cl) is added to this solution, the following equilibrium is established. [CoCI(H20)s] (aq)+ Cl (aq) [CoCl2(H20)2](aq) + 3H20(1) AH >0 Where [CoCl2(H20)2] is also soluble in water. a) Write a Keq expression for this equilibrium b) Suppose we systematically add increasing amounts of Cr to this system, while maintaining a constant solution temperature. Predict the effect of such additions (and briefly explain your reasoning) i) On the preferred coordination of Co i) On the experimental color 2+ ii) On the numerical value Keq When we dissolve CoCl2 in a mixture of water and hydrochloric acid, the resulting solution is purple. Will heating cause the solution to become pink or blue? Briefly explain. c)

Answer 1