The Haber process

Making ammonia

Ammonia is an important industrial product used to make fertilisers, explosives and dyes. It is manufactured using the Haber process. This involves a reversible reaction between nitrogen and hydrogen:

N2(g) + 3H2(g) ⇌ 2NH3(g)

The reaction can reach a dynamic equilibrium.

Hydrogen from natural gas and nitrogen from air are combined at a pressure of 200 atmospheres and a temperature of 450 degrees Celsius using an iron catalyst, to produce ammoniaThe main stages in the Haber process

In the Haber process:

  1. nitrogen (extracted from the air) and hydrogen (obtained from natural gas) are pumped through pipes
  2. a compressor increases the gas pressure to 200 atmospheres
  3. the pressurised gases are heated to 450°C and passed through a reaction chamber containing an iron catalyst to speed up the reaction
  4. the reaction mixture is cooled so that ammonia liquefies and can be removed
  5. unreacted nitrogen and hydrogen are recycled

The conditions are chosen to ensure the process of making ammonia is as profitable as possible.


Explain why iron is used in the Haber process.

Iron is a catalyst for the reaction. It increases the rate of the reaction without being used up in the reaction.


State the reaction conditions used in the Haber process.

A pressure of 200 atmospheres.

A temperature of 450°C.

An iron catalyst.