Onsider this reversible reaction:

PCl5 (g) + heat ↔ PCl3 (g) + Cl2 (g)

Which change to the system will cause equilibrium to shift right and produce more PCl3?

You can shift the equilibrium to the right if you

• Increase the concentration of PCl_5

• Increase the temperature

• Decrease the concentration of Cl_2

• Decrease the total pressure of the system

Decreasing the concentration of PCl_3 will shift the equilibrium to shift to the right, but there will be less PCl_3 at the new equilibrium.

PCl₅ (g) + heat ↔ PCl₃ (g) + Cl₂ (g)

On increasing the concentration of PCl5 (g), the equilibrium will shift in forward direction and produce more PCl₃.

Explanation:

According to Le Chatlier's Principle " If we apply any external stress on a system at equilibrium, the system minimize the effect by itself to regain equilibrium". In above reaction initially the system is in equilibrium. when we increase the concentration of reactant (PCl₅), the system goes to forward and produce more product (PCl₃).

After some time reaction will go in backward direction to regain equilibrium position while consuming PCl₃ and Cl₂. Finally reaction will again in equilibrium position.