How does the addition of an inert gas affect a system at equilibrium?

The addition of an inert gas to a system at equilibrium does not affect the position of the equilibrium. This is because an inert gas does not react with the components of the system and, therefore, does not change the concentrations of the reactants or products involved in the equilibrium reaction.

When an inert gas is added at constant volume, the total pressure of the system will increase due to the added gas; however, the partial pressures of the reactants and products remain unchanged. Since equilibrium depends on the ratio of the concentrations or partial pressures of the reactants and products, and these ratios do not change with the addition of an inert gas, the equilibrium position remains unaffected.

In contrast, changes in concentration, temperature, or pressure that influence the system will shift the equilibrium according to Le Chatelier's principle, but inert gases simply modify the total atmospheric pressure without altering the balance of the chemical species involved.