Final answer:
For an endothermic reaction like PCl₅(g) ↔ PCl₃(g) + Cl₂(g), removing Cl₂ will shift the equilibrium to the right, decreasing temperature will shift it to the left, increasing the volume will shift it to the right, and adding PCl₃(g) will shift it to the right as well.
Step-by-step explanation:
For the endothermic reaction PCl₅(g) ↔ PCl₃(g) + Cl₂(g), the direction of the equilibrium shift due to different changes can be assessed using Le Chatelier's principle.
- a. Cl₂ is removed: The equilibrium will shift to the right to produce more Cl₂ to counteract its removal.
- b. Temperature is decreased: Since the reaction is endothermic, a decrease in temperature is like removing heat, a 'reactant' in this case, so the equilibrium will shift to the left to produce more heat.
- c. Volume of reaction is increased: Increasing volume causes the system to decrease pressure. For reactions involving gases, if the number of moles of gases on one side is different from the other, the equilibrium will shift towards the side with more moles of gas. In this case, that's the right side.
- d. PCl₃(g) is added: When a reactant is added, the equilibrium shifts to the right to consume the added substance and restore equilibrium.
Raising the temperature for an endothermic reaction is akin to adding a reactant so the equilibrium will shift to the right, towards product formation. In contrast, lowering the temperature causes the equilibrium to shift left. At constant temperature, the reaction quotient can be calculated for determining the direction of equilibrium shift after changes to the system.
Given this equilibrium, when we predict the direction of shift for each stress, we consider these principles to understand how the reaction adapts to changes in its environment, aiming to re-establish equilibrium following Le Chatelier's principle.