Question

Discuss what influence temperature has on molecular motions and how it would impact the reaction in Part II.

Part II. Temperature Dependence in a Complex Ion EquilibriumMetal ions such as Co2+ will form complex ions, where ligands surround the metal ion. A ligand
is either a molecule or ion that donates electron density to the metal ion to form a bond.Examples of ligands include H2O, NH3, Cl-, and OH-. CoCl2(H2O)2 is a complex metal ion withtwo Cl- (chloro) and two H2O (aqua) ligands surrounding the Co2+ in a tetrahedral geometry.Co(H2O)6

2+ is also a complex ion with six water molecules (aqua ligands) surrounding the

central metal ion, Co2+, in an octahedral geometry.

In aqueous solution, we can observe the conversion between the tetrahedral complex ion,
CoCl2(H2O)2, which is blue, and the hydrated octahedral complex ion, Co(H2O)6

2+, which is pink,

according to the following equilibrium.

CoCl2(H2O)2 + 4 H2O  Co(H2O)6

2+  + 2 Cl-

     blue       pink

By dissolving CoCl2∙(H2O)6 in methanol, the solution obtained is between blue and pink.

Answer 1