The yield of ammonia in the Haber process can be optimized by employing high pressure, low temperature, and a catalyst.

The Haber process is a well-established method for synthesizing ammonia from nitrogen and hydrogen gases. This reaction is reversible, meaning it can proceed in both the forward and reverse directions. To achieve the maximum yield of ammonia, it is essential to carefully control the reaction conditions.

High pressure is applied to shift the equilibrium toward the production of ammonia, thereby enhancing its yield. This phenomenon occurs because, on the reactant side, there are four moles of gas ($\text{N}_2 + 3\text{H}_2$), while the product side contains only two moles of gas ($2\text{NH}_3$). According to Le Chatelier’s principle, increasing the pressure will favor the side of the reaction with fewer moles of gas, in this case, the ammonia.

In addition, low temperature is advantageous for increasing the yield of ammonia. The formation of ammonia is an exothermic reaction, which means it releases heat. According to Le Chatelier’s principle, lowering the temperature will shift the equilibrium toward the side that produces heat, thereby favoring the formation of ammonia. However, it is important to note that lower temperatures also slow down the reaction rate. Consequently, a moderate temperature is typically employed in practice to strike a balance between reaction rate and ammonia yield.

Lastly, a catalyst is utilized to accelerate the reaction without altering the position of the equilibrium. In the Haber process, iron is often used as the catalyst. It enhances the reaction rate by providing an alternative pathway with a lower activation energy, allowing the reaction to proceed more swiftly. This acceleration means that the desired equilibrium can be achieved more quickly, ultimately increasing the productivity of the overall process.