10.2.1 Predicting the Effect of Changes

• What does Le Chatelier's Principle state about a system at equilibrium subjected to a change in conditions?

  Equilibrium shifts to counteract
• Increasing temperature in an equilibrium shifts it towards the endothermic direction.
• Changes in pressure only affect equilibria involving gases.
• Match the change with its effect on equilibrium:

  Increase in temperature ↔️ Shifts towards endothermic side

  Increase in pressure ↔️ Shifts towards fewer gas molecules

  Addition of reactants ↔️ Shifts towards products

  Addition of products ↔️ Shifts towards reactants
• What effect does decreasing temperature have on an equilibrium?

  Shifts towards exothermic
• Changes in pressure affect equilibria involving gases only.
• Adding products to an equilibrium system will shift the equilibrium towards the reactants.
• Steps to predict shifts in equilibrium position:

  1️⃣ Consider the change in conditions

  2️⃣ Determine if the reaction is endothermic or exothermic

  3️⃣ Apply Le Chatelier's Principle

  4️⃣ Predict the shift in equilibrium
• How does temperature affect equilibrium in exothermic reactions?

  Decreasing temperature favors forward
• In endothermic reactions, increasing temperature favors the forward reaction to produce more products.
• Increasing pressure in a system with fewer gas molecules on the product side will favor the formation of products.
• Exothermic reactions release heat
• In the endothermic reaction $N_{2}O_{4}(g) \rightleftharpoons 2NO_{2}(g)$, increasing temperature shifts the equilibrium towards $NO_{2}(g)$.
• What does Le Chatelier's Principle state about a system at equilibrium subjected to a change in temperature, pressure, or concentration?

  Counteract the change
• Increasing temperature in an endothermic reaction shifts the equilibrium in the forward
• What effect does increasing pressure have on equilibria involving gases according to Le Chatelier's Principle?

  Favors fewer gas molecules
• Increasing the concentration of reactants in a system at equilibrium shifts the equilibrium towards the products.
• Temperature affects equilibrium based on whether the reaction is endothermic or exothermic
• In endothermic reactions, increasing temperature favors the forward reaction and produces more products.
• What effect does increasing temperature have on exothermic reactions at equilibrium?

  Favors the reverse reaction
• Increasing pressure in a system with unequal gas molecules shifts the equilibrium towards the side with fewer gas molecules.
• In the reaction $N_{2}(g) +$$3H_{2}(g) \rightleftharpoons 2NH_{3}(g)$, increasing pressure shifts the equilibrium to the right
• If the number of gas molecules is equal on both sides of a reaction, pressure changes have no effect on equilibrium.
• Increasing the concentration of reactants in a system at equilibrium shifts the equilibrium towards the products
• What effect does increasing product concentration have on equilibrium according to Le Chatelier's Principle?

  Shifts towards reactants
• Le Chatelier's Principle is used in industrial chemistry to optimize reaction yields by manipulating equilibrium conditions.