A gaseous mixture containing nitrogen and hydrogen was introduced, at a temperature of $500\,\text{K}$, into an evacuated vessel with a volume of $6.0\,\text{dm}^3$. The vessel was then sealed. $\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$ The system was left until equilibrium was established. It was determined that $7.2\,\text{mol}$ of $\text{N}_2$ and $12.0\,\text{mol}$ of $\text{H}_2$ were present in the equilibrium mixture. The equilibrium constant, $K_c$, for this equilibrium has a value of $6.0 \times 10^{-2}$ at $500\,\text{K}$. Calculate the concentration of ammonia in the equilibrium mixture at $500\,\text{K}$.
- A$0.58\,\text{mol dm}^{-3}$
- B$0.76\,\text{mol dm}^{-3}$
- C$3.5\,\text{mol dm}^{-3}$
- D$27\,\text{mol dm}^{-3}$