Le Chatelier's Principle

R2.3.4.

State the ‘goal’ of a reaction.

going back to stability or equilibrium

Describe Le Chatelier’s Principle

If a stress is applied or there is a change in the environment of a system at equilibrium, the position of the equilibrium will shift towards the direction that favors equilibrium/ direction that relieves the applied stress to reach a new equilibrium.

State the four stressors of a system at equilibrium.

• Concentration

• Pressure (and therefore Volume)

• Temperature

• Catalysts

State why value of Kc (equilibrium constant) does not change when concentrations, pressures, or catalysts are changed and added.

Kc values only change based on changes in temperature.

State why catalysts do not affect the equilibrium of a system.

• reduces activation energy for both reverse and forward reactions.

  • reduces same amount of rate of reverse and forward reaction

• does not affect the concentration of product or reactant

Define pH

-log[H⁺]

State the relationship between pH and acid concentration.

inverse