Question #44563

Consider the thermodynamic and spectroscopic profile of the following ligand exchange equilibrium in an aqueous medium at $1\text{ atm}$:

$\ce{[Co(H2O)6]^2+ (aq) + 4Cl^- (aq) <=> [CoCl4]^2- (aq) + 6H2O (l)}$

Upon heating the solution from $298\text{ K}$ to $350\text{ K}$, the color transitions from pale pink to intense deep blue. Identify the correct set of statements regarding this transformation:

I. The forward reaction is entropically driven ($\Delta S^\circ > 0$) due to the release of water molecules, which compensates for the endothermic enthalpy change ($\Delta H^\circ > 0$) at higher temperatures. II. The intense deep blue color of the product is primarily attributed to an increase in the magnitude of the Crystal Field Splitting Energy (CFSE) upon replacing $\ce{H2O}$ with $\ce{Cl^-}$. III. The d-d transitions in the blue complex are Laporte partially allowed due to p-d orbital mixing in a non-centrosymmetric geometry, leading to a higher molar extinction coefficient ($\epsilon$). IV. The spin-only magnetic moment ($\mu_s$) increases significantly because the complex transitions from a low-spin octahedral to a high-spin tetrahedral geometry. V. The endothermicity of the forward reaction is heavily influenced by the high desolvation energy of the $\ce{Cl^-}$ ions and the cleavage of six $\ce{Co-O}$ bonds.