At equilibrium, a mixture of N_2, H_2, and NH_3 gas at 500°C is determined to consist of 0.602 mol/L of N_2, 0.420 mol/L of H_2, and 0.113 mol/L of NH_3. What is the equilibrium constant for the reaction N_2(g) + 3H_2(g) ⇄ 2NH_3(g) at this temperature?