Chemical Formula
The main chemical formula for the process is NH3. It has a trigonal pyramidal structure, with 3 single-bonded hydrogens on one side, and a lone pair on the other. The process itself involves nitrogen (derived from air-separation) and hydrogen (derived from natural gas) being inserted into the reaction chamber at a ratio of 1 to 3 by volume, in the presence of a—typically—iron catalyst at a temperature of four hundred to four hundred and fifty degrees Celsius and a pressure of two hundred atmospheres. The triple bonds of diatomic nitrogen make it relatively inert, making the process sluggish under normal conditions. As a result—even though the reaction is, in theory, exothermic, both high temperature and high pressure are needed to drive it forward at a reasonable rate. As such, the process is incredibly energy intensive—to the point of taking up 1 to 2 percent of the global energy production.
Ammonia is a pungent, colorless gas with a boiling point and freezing point of −33.35 °C and −77.7 °C respectively. It is a polar molecule and it has strong intermolecular hydrogen bonds. Ammonia is also highly soluble in water due to its polarity, it dissolves in water with the liberation of heat and, as a weak base, releases hydroxide ions (Zumdahl, 2025, Physical properties of ammonia).
Chemical Reaction
Gaseous diatomic atmospheric nitrogen (derived from air-separation) and gaseous diatomic hydrogen (derived from natural gas) at a ratio of 1:3 by volume are inserted into the reaction chamber in a presence of an iron catalyst at a temperature of 400-450℃ and a pressure of 200 atm. The forward reaction is exothermic, with an enthalpy of roughly -92 kJ/mol.
Key properties of the Haber-Bosch process
The triple bonds in diatomic nitrogen make it relatively inert, resulting in the Haber-Process being sluggish under normal conditions. As a result—even though the reaction is, in theory, exothermic (i.e. it produces heat), both high temperature and high pressure are needed to drive it forward at a reasonable rate.
Considering both the above and the energy needed to produce purified hydrogen and nitrogen, the Haber-Bosch process is incredibly energy intensive—to the point of taking up 1-2% of the global energy production (Lehigh University, 2018, para. 4).
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