AP Chemistry: Le Chatelier's Principle

unit 7

Le Chatelier's Principle

If a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to counteract the change. (Also known as a stress to the system)

Changes (or stresses include):

1. Increase/decrease of reactant or product concentration

2. Increase/decrease pressure

3. Increase/decrease of temperature

increase reactants

shift right, K unchanged

decrease reactants

shift left, K unchanged

increase products

shift left, K unchanged

decrease products

shift right, K unchanged

increase pressure (decrease volume)

shift towards fewest moles of gas, K unchanged

decrease pressure (increase volume)

shift towards most moles of gas, K unchanged

increase temperature

shift right, increase K (endothermic)

decrease temperature

shift left, decrease K (endothermic)

increase temperature

shift left, decrease K (exothermic)

decrease temperature

shift right, increase K (exothermic)

addition of a catalyst

no change; achieve equilibrium faster