Chapter 21, Problem 99RQ

Interpretation Introduction

Interpretation:

The reason for the stability of the $\text{cobalt}\left(\text{III}\right)$ complex as compared to $\text{cobalt}\left(\text{II}\right)$ species is to be explained. The reduction potential of the complex ion ${\left[\text{Co}{\left({\text{NH}}_{\text{3}}\right)}_{\text{6}}\right]}^{\text{2+}}$ and the stronger oxidizing agent among ${\text{[Co}{\left({\text{NH}}_{\text{3}}\right)}_{\text{6}}\text{]}}^{\text{3+}}$ and ${\left[\text{Co}{\left({\text{H}}_{\text{2}}\text{O}\right)}_{\text{6}}\right]}^{\text{3+}}$ are to be determined.

Concept Information:

Crystal field theory is the theory that explains the bonding of the complex ions.

Ligands are the molecules or ions that are bonded with a coordinate covalent bond to a metal ion.

The Crystal Field Stabilization energy CFSE is the energy generated by the distribution of the electrons in the $d$ orbitals of a transition metal ion in the crystal field caused by ligands field geometry.

The cell potential for the reaction can be determined by the standard free energy:

$\Delta G°=-nFE°$.

The relation between standard free energy and the equilibrium constant for a reaction is also given by:

$\Delta G°=-RT\ln K$.