Final answer:
Le Châtelier’s principle explains the common ion effect through a change in concentration, with the equilibrium adjusting to reduce the effects of this change.
Step-by-step explanation:
Le Châtelier’s principle explains the common ion effect through a change in concentration. When a system at equilibrium experiences an increase in the concentration of one of the components, the system will adjust to counteract this change.
For example, if additional ions are added to a solution at equilibrium, the equilibrium will shift to reduce the concentration of the added ions, either by forming a precipitate or by favoring the formation of more reactants.
Changes in pressure and volume primarily affect gas-phase reactions, especially when there is an unequal number of gas molecules on each side of the reaction. A rise in pressure by decreasing volume will shift the equilibrium toward the side with fewer moles of gas.