According to Le Chatelier's principle, if a system at equilibrium is subjected to a change in pressure, the system will adjust itself to counteract the change and restore a new equilibrium. In this case, increasing the pressure will cause the reaction to shift in the direction that has fewer moles of gas to reduce the pressure.For the reaction N2 g + 3 H2 g 2 NH3 g , there are 4 moles of gas on the reactant side 1 mole of N2 and 3 moles of H2 and 2 moles of gas on the product side 2 moles of NH3 .When the pressure is increased, the equilibrium will shift towards the side with fewer moles of gas, which is the product side formation of ammonia . This means that the reaction will proceed in the forward direction, producing more ammonia and consuming nitrogen and hydrogen.