To calculate the equilibrium constant K for the given reaction, we need to know the equilibrium concentrations of the reactants and products. However, you have only provided the temperature and pressure of the system. If you have the equilibrium concentrations or partial pressures of the reactants and products, you can use the following equation to calculate K:K = [NH3]^2 / [N2] * [H2]^3 Alternatively, if you have the Gibbs free energy change G for the reaction at the given temperature, you can calculate K using the following equation:K = exp -G / R * T Where R is the gas constant 8.314 J/molK and T is the temperature in Kelvin 400C = 673.15 K .Please provide the equilibrium concentrations or partial pressures of the reactants and products, or the Gibbs free energy change for the reaction at the given temperature, so that I can help you calculate the equilibrium constant.