For the reaction , a reaction mixture contains partial pressures , , and at . If at this temperature — Chemical Equilibrium Chemistry Question
Question
For the reaction $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$, a reaction mixture contains partial pressures $P_{H_2} = 2\text{ atm}$, $P_{N_2} = 1\text{ atm}$, and $P_{NH_3} = 3\text{ atm}$ at $725\text{ K}$. If $K_p = 4.28 \times 10^{-5}\text{ atm}^{-2}$ at this temperature, which of the following is correct?
💡 Solution & Explanation
The reaction quotient $Q_p$ is calculated using partial pressures: $Q_p = \frac{(P_{NH_3})^2}{(P_{N_2})(P_{H_2})^3} = \frac{(3)^2}{(1)(2)^3} = \frac{9}{8} = 1.125\text{ atm}^{-2}$. Comparing $Q_p$ with $K_p$: $1.125 \gg 4.28 \times 10^{-5}$. Since $Q_p > K_p$, the net reaction will proceed in the backward direction.