Final answer:
When an aqueous system is diluted, the equilibrium shifts to the side with the greater number of moles of dissolved species, favoring the forward reaction and producing more particles to re-establish equilibrium.
Step-by-step explanation:
When an aqueous system is diluted, the principle of Le Chatelier states that the equilibrium will shift in the direction that counteracts the change. In the context of dilution, this means that the equilibrium shifts to the side with the greater number of moles of dissolved species. For a reversible reaction such as the one involving hydrogen iodide (HI), hydrogen (H₂), and iodine (I₂), if the system is initially at equilibrium with more HI (product) present than H₂ and I₂ (reactants), dilution would cause the equilibrium to shift to the reactant side. This phenomenon occurs because by increasing the volume of the system, the concentration of all species is reduced, and thus, the reaction will progress in the direction that produces more particles to re-establish equilibrium. This is generally referred to as the reaction shifting to favor the forward reaction when diluting.