Consider the reaction N2(g) + 3 H2(g) <=> 2 NH3(g), which is exothermic as written. What would be the effect on the equilibrium position of adding N2(g)?

Shift to the right side

Explanation:

Remember that any stress that we bring to a chemical equilibrium, will be answered by this in such a way as to minimize the disturbance and attain equilibrium again. This is known as LeChatelier´s principle.

If we add N₂(g) to the system at equilibrium

N₂ ( g) + 3 H₂(g)   ⇄ 2 NH₃(g)

the equilibrium will consume part of the added N₂ gas until it reaches equilibrium again producing more ammonia (NH₃).

Mathematically this is equivalent to a  decrease the pressure of N₂ so that the equilibrium partial pressures of the gases obey the equilbrium pressure constant Kp.

Therefore the equilibrium will shift to the product side.