Question

Consider a reaction:
$S{O}_{2}C{l}_2\left(g\right)\rightleftharpoons S{O}_2\left(g\right)+C{l}_2\left(g\right)$
Equilibrium is attained at ${25}^{\circ }C$ in a closed container.
At equilibrium, 2 moles of an inert gas Helium $\left(He\right)$ are introduced .
Which of the following statements is correct?

• A. Concentrations of both $S{O}_2,C{l}_2$ doubles.
• B. There will be no effect on the equilibrium.
• C. Only concentration of $S{O}_2$ is reduced by half.
• D. Twice the amount of $S{O}_{2}C{l}_2$ is formed.

Answer 1

The correct option is B There will be no effect on the equilibrium.

In a closed container, the volume is constant. So, addition of inert gas $He$ will be at a constant volume.

When an inert gas is added to the system in equilibrium at constant volume, the total pressure will increase. But the concentrations of the products and reactants (i.e. ratio of their moles to the volume of the container) will not change or we can say partial pressure of reactant or product does not change.
Hence, when an inert gas is added to the system in equilibrium at constant volume there will be no effect on the equilibrium.