Le Chateliers Principle Main Concept Systems at equilibrium

Le Chatelier’s Principle Main Concept: Systems at equilibrium respond to disturbances by partially countering the effect of the disturbance (Le Chatelier’s principle).

Le Chatelier’s Principle Purpose Stress Addition/Removal of Chemical Species Volume/Pressure Changes Temperature Changes Effect/Shift

- Le Chatelier’s principle can be used to predict the response of a system to stresses: addition or removal of a chemical species, change in temperature, change in volume/pressure of a gas phase system, and dilution of a reaction system with water or other solvent

- Le Chatelier’s principle can be used to reason about the effects a stress will have on experimentally measurable properties, such as p. H, temperature, and color of a solution

Le Chatelier’s Principle Rules: Adding chemical species: shifts equilibrium away from chemical species side Removing chemical species: shifts equilibrium towards chemical species side Increasing pressure (decreasing volume): shifts equilibrium towards side with less moles Decreasing pressure (increasing volume): shifts equilibrium towards side with more moles

Le Chatelier’s Principle Rules: Increasing Temperature: Endothermic Reactions: shifts equilibrium towards products Exothermic Reactions: shifts equilibrium towards reactants Decreasing Temperature: Endothermic Reactions: shifts equilibrium towards reactants Exothermic Reactions: shifts equilibrium towards products