Le Châtelier's principle Knowledge-Based Download PDF

Questions

1. 1.

   Consider the heterogeneous reaction at dynamic equilibrium in a closed vessel: $\text{CaCO}_3(s) \rightleftharpoons \text{CaO}(s) + \text{CO}_2(g) \quad \Delta H > 0$ Which of the following changes will result in an increase in the equilibrium concentration of $\text{CO}_2(g)$?

   • A) Adding more $\text{CaCO}_3(s)$ at constant temperature
   • B) Removing half of the $\text{CaO}(s)$ at constant temperature
   • C) Compressing the container to reduce its volume at constant temperature
   • D) Increasing the temperature of the container
2. 2.

   Consider the following reversible gaseous reaction at dynamic equilibrium in a container fitted with a movable piston: $\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g) \quad \Delta H < 0$ Which of the following modifications will cause the equilibrium position to shift toward the reactants (to the left)?

   • A) Decreasing the temperature of the system at constant volume
   • B) Decreasing the volume of the reaction container at constant temperature
   • C) Injecting additional $\text{N}_2(g)$ into the vessel at constant volume
   • D) Introducing argon gas into the vessel at constant temperature and total pressure
3. 3.

   Consider the following reversible reaction at dynamic equilibrium in a closed vessel: $$\text{H}_2(g) + \text{I}_2(g) \rightleftharpoons 2\text{HI}(g) \quad \Delta H > 0$$ Which of the following disturbances will not cause a shift in the position of equilibrium?

   • A) Increasing the temperature of the reaction vessel
   • B) Injecting additional $\text{H}_2(g)$ into the vessel at constant volume
   • C) Decreasing the volume of the reaction vessel at constant temperature
   • D) Selectively removing $\text{HI}(g)$ from the reaction mixture
4. 4.

   A gaseous reaction is at dynamic equilibrium in a closed vessel according to the following endothermic equation: $$\text{PCl}_5(g) \rightleftharpoons \text{PCl}_3(g) + \text{Cl}_2(g) \quad \Delta H > 0$$ Which of the following modifications will shift the equilibrium position toward the reactants?

   • A) Increasing the temperature of the system
   • B) Increasing the volume of the system at constant temperature
   • C) Adding a suitable catalyst to the reaction mixture
   • D) Decreasing the temperature of the system
5. 5.

   Consider the following gaseous reaction at dynamic equilibrium in a closed vessel: $$2\text{SO}_2(g) + \text{O}_2(g) \rightleftharpoons 2\text{SO}_3(g) \quad \Delta H < 0$$ Which of the following changes will cause an increase in the equilibrium yield of $\text{SO}_3(g)$?

   • A) Increasing the temperature of the system
   • B) Increasing the volume of the reaction vessel
   • C) Decreasing the temperature of the system
   • D) Adding an inert gas at constant volume