Question

Equilibrium constant, Kc for the reaction
$N_2 (g) + 3H_2 (g) ⇋ 2NH_3 (g)$
At 500 K is 0.061 At a particular time, the analysis shows that composition of the reaction mixture is 3.0 mol L–1 N2, 2.0 mol L–1 H2 and 0.5 mol L–1 NH3. Is the reaction at equilibrium? If not in which direction does the reaction tend to proceed to reach equilibrium?

Answer 1

The given reaction is :
$N_2(g) \+ 3H_2(g) ↔ 2NH_3(g)$
At a particular time : 3.0 mol L-1 2.0 mol L-1 0.5 mol L-1

Now, we know that,
$Q_c = \frac {[NH_3]^2}{[N_2][H_2]^3}$

$Q_c= \frac {(0.5)^2}{(3.0)(2.0)^3}$
$Q_c= 0.0104$
It is given that $K_c = 0.061$.
Since $Q_c ≠ K_c$ , the reaction is not at equilibrium.
Since $Q_c < K_c$, the reaction will proceed in the forward direction to reach equilibrium.