What happens to equilibrium when pressure is decreased?

In a chemical equilibrium involving gases, changes in pressure can affect the position of the equilibrium according to Le Chatelier's principle. When pressure is decreased, the equilibrium shifts toward the side of the reaction that produces more moles of gas. This occurs because the system seeks to counteract the change by increasing the pressure, which can be achieved by favoring the formation of more gas molecules.

In a reaction where one side has fewer gas moles compared to the other, decreasing pressure effectively encourages the formation of additional gas to re-establish equilibrium. This shift results in an increase in the total number of gas moles in the system, counterbalancing the reduction in pressure. Understanding this concept is crucial for predicting how changes in external conditions can influence the outcome of chemical reactions.