Le Chatelier's Principle Examples: Real-World Applications

🧪 Quick Study Guide

• 🔥 Le Chatelier's Principle states that if a change of condition is applied to a system in equilibrium, the system will shift in a direction that relieves the stress.
• 🌡️ The 'conditions' or 'stresses' typically include changes in concentration, temperature, pressure, or the addition of an inert gas.
• 📈 Concentration: Adding more reactants shifts the equilibrium to the products; adding more products shifts it to the reactants.
• ❄️ Temperature: For an endothermic reaction (heat is absorbed, $\Delta H > 0$), increasing temperature shifts the equilibrium to the products. For an exothermic reaction (heat is released, $\Delta H < 0$), increasing temperature shifts the equilibrium to the reactants.
• 💨 Pressure: Increasing pressure shifts the equilibrium towards the side with fewer moles of gas. Decreasing pressure shifts it towards the side with more moles of gas. If the number of moles of gas is the same on both sides, pressure has no effect.
• 🧮 Catalysts: Catalysts speed up the rate at which equilibrium is reached, but they do not affect the position of the equilibrium.

🤔 Practice Quiz

1. What happens to the equilibrium of the Haber-Bosch process ($N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$, $\Delta H < 0$) if the temperature is increased?
   1. A. The equilibrium shifts towards the formation of $NH_3$.
   2. B. The equilibrium shifts towards the formation of $N_2$ and $H_2$.
   3. C. The equilibrium does not shift.
   4. D. The reaction rate decreases, but the equilibrium remains the same.
2. In the reaction $CO(g) + 2H_2(g) \rightleftharpoons CH_3OH(g)$, what happens if the pressure is increased?
   1. A. The equilibrium shifts to the left.
   2. B. The equilibrium shifts to the right.
   3. C. There is no change in the equilibrium.
   4. D. The reaction stops.
3. Which of the following will NOT shift the equilibrium position in the reaction $H_2(g) + I_2(g) \rightleftharpoons 2HI(g)$?
   1. A. Adding $H_2(g)$
   2. B. Adding $HI(g)$
   3. C. Increasing the pressure
   4. D. Adding $I_2(g)$
4. For an endothermic reaction, what is the effect of decreasing the temperature?
   1. A. Shifts equilibrium to the products.
   2. B. Shifts equilibrium to the reactants.
   3. C. No effect on equilibrium.
   4. D. Increases the reaction rate.
5. How does adding a catalyst affect a system at equilibrium?
   1. A. Shifts equilibrium to the products.
   2. B. Shifts equilibrium to the reactants.
   3. C. No effect on equilibrium position.
   4. D. Changes the value of the equilibrium constant.
6. In the reaction $2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)$, increasing the concentration of $SO_2$ will:
   1. A. Shift the equilibrium to the left.
   2. B. Shift the equilibrium to the right.
   3. C. Have no effect on the equilibrium.
   4. D. Decrease the amount of $O_2$.
7. Consider the equilibrium $N_2O_4(g) \rightleftharpoons 2NO_2(g)$. If you increase the volume of the container, what will happen?
   1. A. The equilibrium will shift to the left.
   2. B. The equilibrium will shift to the right.
   3. C. There will be no change in the equilibrium.
   4. D. The total pressure will increase.