Le Chatelier’s principle when a chemical system at equilibrium is disturbed, it reattains
equilbrium by undergoing a net reaction that reduces the effect of the disturbance.
• If the concentration increases, the system reacts to consume some of it
• If the concentration decreases, the system reacts to produce some of it.
• The equilibrium position shifts to the right when a component on the left is added.
• The equilibrium position shifts to the left when a component on the left is
• EQ P shifts to the right if a reactant is added or a product is removed; reactant
increases or product decreases
• EQ P shifts to the left if a reactant is removed or a product is added: reactant
decreases or product increases.
• Adding an inert has no effect on the equilibrium position. Adding an inert gas
does not change the volume so all reactant and product concentrations remain the
• Changing the volume causes a large shift in equilibrium.
• A change in volume results in a change in concentration. A decrease in volume
raises concentration and an increase in volume lowers concentration.
• A change in pressure due to a change in volume does not alter Kc.
• IF the volume become smallers and pressure increases the reaction shifts so that
the total number of gas molecules decreases.
• If the volume becomes larger and pressure is lower the reaction shifts so that the
total number of gas molecules increases.
• Only temperature can alter K
• A temperature increases adding heat favors the endothermic heat absorbing
direction and a temperature decrease removing heat favors the exothermic heat
• A temperature rise will increase K for a system with a positive H rxn.
• A temperature rise will decrease K for a system with a negative Hrxn.
• A catalyst shorterns the time it takes to reach equilibrium but has no effect on the
equilibrium position. Chapter 18:
• An acid is a substance that has H in its formul