Water and chlorine, each at 1 atm pressure, are placed in a closed container at 375 K - VCE - SSCE Chemistry - Question 7 - 2002 - Paper 1

To determine the correct relationship at equilibrium, we analyze the equilibrium constant expression:

$K = \frac{[HCl]^4 [O_2]}{[H_2O]^2 [Cl_2]^2}$.

Given that $K$ is a large number ($5 \times 10^4$), this indicates that the products are favored at equilibrium over the reactants.

1. Produit Concentrations: This means that the concentration of $[HCl]$ and $[O_2]$ must be significantly greater than that of the reactants ($[H_2O]$ and $[Cl_2]$).
2. Shorten Expressive Terms: Rearranging the formula indicates that the concentration of $[Cl_2]$ would be less than the double of $[HCl]$ (i.e., $2[Cl_2] < [HCl]$).
3. Conclusion: Thus, the only statement that holds true is $2[Cl_2] > [HCl]$, confirming Option B is valid.