Examples of Le Chatelier's Principle: Pressure and Volume Effects

📚 Quick Study Guide

• ⚖️ Le Chatelier's Principle states that if a system at equilibrium is subjected to a change, the system will adjust itself to counteract the change and restore a new equilibrium.
• 💨 For gaseous reactions, increasing pressure favors the side with fewer moles of gas.
• 🎈 Conversely, decreasing pressure favors the side with more moles of gas.
• 🌡️ Changes in volume directly affect pressure. Decreasing volume increases pressure, and increasing volume decreases pressure.
• ⚗️ These effects are most significant when there's a difference in the number of gaseous molecules between reactants and products.
• 📝 Remember, adding an inert gas at constant volume does *not* shift the equilibrium.
• ➗ The reaction quotient, $Q$, can help predict the shift. If $Q < K$, the reaction shifts right. If $Q > K$, the reaction shifts left.

🧪 Practice Quiz

1. Which of the following changes will shift the equilibrium of the reaction $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$ to the right?
   1. Increasing the volume of the container.
   2. Decreasing the pressure by adding an inert gas.
   3. Increasing the pressure by decreasing the volume.
   4. Adding more $NH_3(g)$.


2. Consider the reaction $2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)$. If the pressure is increased, what will happen to the amount of $SO_3(g)$ at equilibrium?
   1. It will decrease.
   2. It will increase.
   3. It will remain the same.
   4. It will fluctuate unpredictably.


3. For the reaction $CO(g) + Cl_2(g) \rightleftharpoons COCl_2(g)$, which change favors the formation of $COCl_2(g)$?
   1. Increasing the volume.
   2. Decreasing the pressure.
   3. Increasing the pressure.
   4. Adding an inert gas at constant pressure.


4. Which of the following reactions is NOT affected by a change in pressure?
   1. $2NO_2(g) \rightleftharpoons N_2O_4(g)$
   2. $H_2(g) + I_2(g) \rightleftharpoons 2HI(g)$
   3. $PCl_5(g) \rightleftharpoons PCl_3(g) + Cl_2(g)$
   4. $2SO_3(g) \rightleftharpoons 2SO_2(g) + O_2(g)$


5. If the volume of a container containing the reaction $N_2O_4(g) \rightleftharpoons 2NO_2(g)$ is doubled, what will happen to the equilibrium?
   1. Shift to the left.
   2. Shift to the right.
   3. No change.
   4. The reaction will explode.


6. Consider the equilibrium: $A(g) + 2B(g) \rightleftharpoons C(g)$. What happens to the equilibrium if the partial pressure of A is increased?
   1. The equilibrium shifts to favor the reactants.
   2. The equilibrium shifts to favor the products.
   3. There is no change in the equilibrium position.
   4. The reaction rate decreases.


7. Which statement is correct regarding the effect of increasing pressure on the following reaction: $2A(g) + B(g) \rightleftharpoons 3C(g)$?
   1. The equilibrium shifts towards the side with more moles of gas (reactants).
   2. The equilibrium shifts towards the side with fewer moles of gas (products).
   3. The equilibrium remains unchanged.
   4. The reaction rate decreases significantly.