Consider the reaction: PCl₅(g) \(\rightleftharpoons\) PCl₃(g) + Cl₂(g) in a closed container at equilibrium. At a fixed temperature, what will be the effect of adding more PCl₅ on the equilibrium concentration of Cl₂(g) ?

CONCEPT:

Le Chatelier's Principle

• Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to counteract the change.
• In the context of chemical reactions, adding more reactants or products will shift the equilibrium to minimize the disturbance.

APPLICATION:

• Consider the reaction: PCl5(g) ⇌ PCl3(g) + Cl2(g)
• At equilibrium, the concentrations of PCl5, PCl3, and Cl2 are constant.
• When more PCl5 is added, the system is disturbed as the concentration of PCl5 increases.
• According to Le Chatelier's Principle, the equilibrium will shift to the right to reduce the disturbance by producing more PCl3 and Cl2.

CONCLUSION:

• Adding more PCl5 increases the concentration of PCl5.
• The equilibrium shifts to the right, resulting in an increase in the concentration of Cl2.
• Therefore, the correct answer is option 2: It increases.

The correct answer is option 2: It increases.