Question

For the reaction: $PC{l}_5\left(g\right)\rightleftharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right)$, the forward reaction is favoured by:

• A. Introducing an inert gas at a constant volume
• B. Introducing chlorine gas at a constant volume
• C. Introducing an inert gas at a constant pressure
• D. Increasing the volume of the container

Answer 1

Answer: (C), (D)

The correct options are
C Introducing an inert gas at a constant pressure
D Increasing the volume of the container

Introducing an inert gas at a constant pressure will change the partial pressure of all reactants since the total volume increases. This would increase the rate of forward reaction if $\Delta n>0$ and will favour the backward reaction if $\Delta n<0$, where $\Delta n=$ moles of product $-$moles of reactants.
Increasing the volume of the container reduces the pressure inside the container which shifts the equilibrium in a direction where the number of moles increases.