What change occurs when the pressure in a gaseous reversible reaction is increased?

When the pressure in a gaseous reversible reaction is increased, the equilibrium shifts towards the side with fewer moles of gas. This principle is based on Le Chatelier's principle, which states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change.

In a gas-phase reaction, increasing the pressure affects the relative concentrations of the gaseous reactants and products. The system will adjust to lower the pressure, which generally involves favoring the side of the reaction that has fewer moles of gas. This shift helps to alleviate the pressure increase by reducing the total number of gas particles in the system, thereby allowing the reaction to reach a new equilibrium under the altered conditions.

This is a crucial concept in understanding how changes in pressure can influence the direction of a reaction and the yield of products in industrial applications, as well as in laboratory settings.