Handout: Le Chatelier’s Principle Summary
Stress
Shift
What Occurs (Why?)
Effect on K
Increase in concentration of a
substance
away from substance
Added substance is
removed
None
(addition of reactant/product)
(shifts to consume)
Decrease in concentration of a towards substance
substance
Production of removed
substance (shifts to
replace)
(removal of reactant/product)
Increase pressure of system
(decrease the volume)
Decrease pressure of system
(increase volume)
Increase temperature of the
system
(addition of heat/energy)
Decrease the temperature of
system
None
towards fewer moles of Shifts to relieve the
gas
added pressure
None
towards more moles of
gas
None
Shifts to make up lost
pressure
Shifts to consume added
endothermic reaction is heat/energy
favoured
K ↓ (exo)
towards heat/energy
Shifts to produce
heat/energy (to make up
for loss)
K ↑ (exo)
away from heat/energy
K ↑ (endo)
(remove heat/energy)
exothermic reaction is
favoured
Add a catalyst
NO SHIFT
Rates of both forward
and reverse reaction are
increased.
None
Add inert gas
NO SHIFT
Total pressure of system
increased (at fixed V).
Partial pressures remain
the same (ratio is
unchanged)
None
© M. Gedik, Department of Chemistry, University of Alberta (2018)
K ↓ (endo)