The relationship between the equilibrium constant, $K_{eq}$, and $\Delta G^\circ$ for any reaction is shown in the graph, for a limited range of $\Delta G^\circ$ values - HSC - SSCE Chemistry - Question 37 - 2024 - Paper 1

The graph indicates that reactions with large negative $\Delta G^\circ$ values correspond to extremely large equilibrium constants, implying that these reactions will proceed effectively to completion.

For the given reaction, we calculate:

$\Delta G^\circ = \Delta H^\circ - T\Delta S^\circ = -217 \text{ kJ mol}^{-1} - (-3 \text{ kJ mol}^{-1}) = -214 \text{ kJ mol}^{-1}$

This value of $\Delta G^\circ$ is large and negative, which signifies that the reaction has a strong tendency to proceed to completion. The substantial negative value of $\Delta H^\circ$ indicates that the reaction is highly exothermic, while the small $T\Delta S^\circ$ term contributes little to the overall Gibbs free energy change.

Thus, due to the significant negative $\Delta H^\circ$ relative to the $T\Delta S^\circ$, this reaction predominantly moves toward completion, rather than achieving a state of equilibrium.