Equilibrium Effects

Major points on Equilibrium:

Temperature:

Temperature dependence of an equilibrium is due to the exothermic or endothermic nature of a reaction.

Driving the equilibrium forward in an exothermic reaction requires a decrease in temperature.
Driving the equilibrium forward in an endothermic reaction requires an increase in temperature.

Pressure:

Pressure is solely dependent on PARTIAL pressure on the equilibrium. Changing the pressure of the container so that the concentration of the products and reactants remain the same does not effect the equilibrium.

IMPORTANT: Inserting an inert gas into the equilibrium will not affect the equilibrium.

The equilibrium will shift to favour the side with LESS moles of gas with an increase in pressure.

Product or Reactant Concentrations:

Similarly an increase in reactant concentrations will shift the equilibrium in the forward direction. Conversely an increase in the reactant concentrations will shift the equilibrium in the reverse direction.

The converse applies, if you decrease the reactants the equilibrium will be shifted in the reverse direction. Decrease the products and the equilibrium will be shifted in the forward direction.

Other Points:

  • They are dynamic and involve reversible reactions, and can only be achieved in a closed system.
  • Equilibrium is achieved when the rate of the forward reaction is equal to the backward reaction.
  • The position of the equilibrium describes the relative proportions of the reactants and products at equilibrium. It depends on the pressure, volume, concentration of both products and reactants, and the temperature.
  • Le Chatelier's Principle can be used to predict the response of an equilibrium system to a change in the conditions.