Changes in pressure can also affect the position of equilibrium in reactions involving gases.
For example, consider this reaction:
N2 (g) + 3H2 (g) ⇌ 2NH3 (g)
Therefore, an increase in pressure will shift the position of equilibrium of the right, producing more NH3. This will produce the fewest number of gas molecules. Conversely, a decrease in pressure will shift the equilibrium to the left, producing more N2 and 3H2, which have a greater number of gas molecules.