Chemistry

The equilibrium constant $K$ tells you the ratio of products to reactants at equilibrium—a huge $K$ means the reaction has gone nearly to completion, while a tiny $K$ means almost nothing reacted. Here, $K = 1.3 \times 10^{10}$ is enormous, so the denominator (reactants) must be vanishingly small compared to the numerator (products) for their ratio to be so large. This means the equilibrium mixture is dominated by $\text{H}_2$ and $\text{I}_2$.

The equilibrium constant $K$ tells you the ratio of products to reactants at equilibrium—a huge $K$ means the reaction has gone nearly to completion, while a tiny $K$ means almost nothing reacted. Here, $K = 1.3 \times 10^{10}$ is enormous, so the denominator (reactants) must be vanishingly small compared to the numerator (products) for their ratio to be so large. This means the equilibrium mixture is dominated by $\text{H}_2$ and $\text{I}_2$.