13-3-shifting-equilibria-le-chateliers-principle_summary

Le Chatelier's principle states that if an equilibrium system is stressed by changes in concentration or temperature, it will respond by shifting in a direction that reduces the stress. 1. Effect of a Change in Concentration: If the concentration of a reactant or product is increased, the equilibrium will shift to counteract the change. For example, adding reactant A in the equilibrium equation A → B will cause the equilibrium to shift right to consume more A and produce more B, while removing product B will cause the equilibrium to shift left to produce more B and consume more A. 2. Effect of a Change in Temperature: Raising the temperature of an endothermic reaction (heat is consumed) will cause the equilibrium to shift to the right as it attempts to consume more heat, while lowering the temperature will cause the equilibrium to shift left to release more heat. For exothermic reactions (heat is produced), the opposite temperature dependence is observed. For gas-phase equilibria, changing the volume can also affect the equilibrium by changing the partial pressure of the gases. However, this does not shift the equilibrium if the number of moles of reactants and products remains the same. If the number of moles is different, changing the volume will cause the equilibrium to shift in a direction that better accommodates the volume change. The principle of Le Chatelier's is relevant to everyday life, such as in the carbonation of soft drinks where changes in pressure affect the dissolution of carbon dioxide, and as a result, the carbonation level of the drink.