R2.3—How far? The extent of chemical change

R2.3.1—A state of dynamic equilibrium is reached in a closed system when the rates of forward and backward reactions are equal.

• Describe the characteristics of a physical and chemical system at equilibrium.

R2.3.2—The equilibrium law describes how the equilibrium constant, K, can be determined from the stoichiometry of a reaction.

• Deduce the equilibrium constant expression from an equation for a homogeneous reaction.

R2.3.3—The magnitude of the equilibrium constant indicates the extent of a reaction at equilibrium and is temperature dependent.

• Determine the relationships between K values for reactions that are the reverse of each other at the same temperature.

R2.3.4—Le Châtelier’s principle enables the prediction of the qualitative effects of changes in concentration, temperature and pressure to a system at equilibrium.

• Apply Le Châtelier’s principle to predict and explain responses to changes of systems at equilibrium.