At equilibrium in a rigid vessel, [PCl5] = 0.20 M, [PCl3] = 0.10 M and [Cl2] = 0.10 M for PCl5(g) PCl3(g) + Cl2(g). Then 0.10 mol/L of Cl2 is injected at constant temperature. Immediately after the addition, Q_c and the direction of the net reaction are

JEE Main levelSingle correct optionDifficulty 2 of 3ce025

At equilibrium in a rigid vessel, $[PCl X_{5}] = 0.20 M$ , $[PCl X_{3}] = 0.10 M$ and $[Cl X_{2}] = 0.10 M$ for $PCl X_{5} (g) PCl X_{3} (g) + Cl X_{2} (g)$ . Then 0.10 mol/L of $Cl X_{2}$ is injected at constant temperature. Immediately after the addition, $Q_{c}$ and the direction of the net reaction are

First

K_{c} = (0.10) (0.10) /0.20 = 0.05

. After adding

Cl X_{2}

[Cl X_{2}] = 0.20

M, so

Q_{c} = (0.10) (0.20) /0.20 = 0.10

. As

Q_{c} > K_{c}

, the net reaction is backward.