Given the reaction: N_2(g) + 3H_2(g) ightleftharpoons 2NH_3(g), the equilibrium constant K for this reaction is:

• A. K = [NH_3]^2 / ([N_2][H_2]^3)
• B. K = [NH_3] / ([N_2][H_2])
• C. K = [N_2][H_2]^3 / [NH_3]^2
• D. K = [N_2][H_2] / [NH_3]

Answer: (A)

Verified step by step guidance

1. Identify the balanced chemical equation: \(\mathrm{N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}\).
2. Recall that the equilibrium constant expression \(K\) is written as the ratio of the product concentrations raised to their stoichiometric coefficients over the reactant concentrations raised to their stoichiometric coefficients.
3. Write the general form of the equilibrium constant expression for this reaction: \(K = \frac{[\mathrm{NH_3}]^{2}}{[\mathrm{N_2}][\mathrm{H_2}]^{3}}\).
4. Note that the exponents correspond to the coefficients in the balanced equation: 2 for \(\mathrm{NH_3}\), 1 for \(\mathrm{N_2}\), and 3 for \(\mathrm{H_2}\).
5. Confirm that the equilibrium constant expression matches the form \(K = \frac{[\mathrm{NH_3}]^{2}}{[\mathrm{N_2}][\mathrm{H_2}]^{3}}\) and not any other variation.