When a reaction is at equilibrium, what happens to the concentration of reactants and products?

When a reaction is at equilibrium, the concentrations of both reactants and products remain constant over time. This does not mean that the reactants and products are equal in concentration, but rather that their rates of formation and consumption are balanced.

At equilibrium, the forward reaction (where reactants turn into products) occurs at the same rate as the reverse reaction (where products turn back into reactants). This dynamic process means that while the actual amounts of reactants and products may not change, they achieve a stable ratio that defines the equilibrium state of the reaction.

In this state, any disturbance could shift the equilibrium according to Le Chatelier's principle, which states that the system will adjust to counteract any changes to concentrations, temperature, or pressure. The key takeaway is that at equilibrium, the concentrations do not vary, indicating a stable condition in the reaction system.