An increase in pressure affects the equilibrium position of a reaction according to Le Chatelier's principle, which states that if a system at equilibrium is subjected to a change in pressure, temperature, or concentration of reactants or products, the system will adjust its equilibrium position to counteract the change.When the volume of a system is decreased, the pressure increases. According to Le Chatelier's principle, the reaction will shift its equilibrium position to counteract this increase in pressure. In a chemical reaction, this means that the reaction will shift in the direction that produces fewer moles of gas, as this will help to reduce the pressure.For example, consider the following equilibrium reaction:N2 g + 3H2 g 2NH3 g In this reaction, there are 4 moles of gas on the left side 1 mole of N2 and 3 moles of H2 and 2 moles of gas on the right side 2 moles of NH3 . If the volume of the system is decreased and the pressure increases, the reaction will shift to the right, towards the side with fewer moles of gas NH3 , in order to reduce the pressure. This shift in the equilibrium position will result in an increase in the concentration of NH3 and a decrease in the concentrations of N2 and H2.In summary, an increase in pressure due to a decrease in volume will cause the equilibrium position of a reaction to shift in the direction that produces fewer moles of gas, according to Le Chatelier's principle.