Answer:
In order to increase the amount of H₂ present, the reaction should be run at high temperatures and low pressures.
Explanation:
Let's consider the following gas phase reaction.
N₂(g) + 3 H₂(g) ⇄ 2 NH₃(g) ΔHº = -92 kJ
To predict how the reaction will proceed when we introduce modifications we need to consider Le Chatelier's Principle: If a system at equilibrium suffers a perturbation, it will react to counteract such perturbation.
ΔHº < 0 means that the reaction is exothermic. If we increase the temperature, the system will decrease it favoring the reverse reaction to absorb heat. As a side-effect the amount of H₂ increases.
If we decrease the pressure, the system will increase it by favoring the reverse reaction so that there are more gaseous moles and more pressure. As a side-effect the amount of H₂ increases.
