Le Chatelier's Principle

What does Le Chatelier's Principle state?

When stress is applied to a system, the system will try to relieve the stress.

Effect of adding reactants

Shift towards products

Effect of adding products

Shift towards reactants

Effect of removing reactants

Shift towards reactants

Effect of removing products

Shift towards products

Which states of matter will only apply for adding/removing reactants?

Gases

Effect of increasing pressure

Shifts towards the side with LESS moles of gas

Effect of decreasing pressure

Shifts towards the side with MORE moles of gas

Effect of pressure on equilibrium when BOTH sides have an equal number of moles of gas

In this case, pressure would have no effect on equilibrium.

Effect of decreasing temperature in an EXOTHERMIC reaction

Shifts towards products (towards the side with the heat)

Effect of decreasing temperature in an ENDOTHERMIC reaction

Shifts towards reactants (towards the side with the heat)

Effect of increasing temperature in an EXOTHERMIC reaction

Shifts towards reactants (away from the side with the heat)

Effect of increasing temperature in an ENDOTHERMIC reaction

Shifts towards products (away from the side with the heat)

When does the K value change?

ONLY when there is a change in temperature

Effect on the K value in an EXOTHERMIC reaction when temperature is increased

Lower K value

Effect on the K value in an EXOTHERMIC reaction when temperature is decreased

Higher K value

Effect on the K value in an ENDOTHERMIC reaction when temperature is increased

Higher K value

Effect on the K value in an ENDOTHERMIC reaction when temperature is decreased

Lower K value

Effect of adding a catalyst

No effect/shift