Responding to equilibrium changes

An equilibrium mixture can respond to changes in concentration, pressure, or temperature. Adding a reactant generally favours the direction that consumes it. A catalyst speeds approach to equilibrium but does not change the equilibrium constant or final equilibrium composition. For a gas reaction at fixed temperature, compression favours the side with fewer gas particles if the two sides have different gas-mole totals. Temperature is different: changing it can change the equilibrium constant itself.