The Haber process produces ammonia from nitrogen and hydrogen gases under high pressure, temperature, and in the presence of an iron catalyst. Temperature and pressure conditions are carefully balanced - high enough for a reasonable reaction rate but not so high that most gases remain unreacted. The process involves continually recycling unreacted gases through the reactor until nearly full conversion to ammonia is achieved. Le Chatelier's principle and considerations of reaction rates and equilibrium guide the optimization of temperature, pressure, and proportions of gases for maximum economical ammonia production.