The Haber process is a reward for HSC chemistry

The Haber process is a financially viable method to produce ammonia from hydrogen and nitrogen. It was first invented in 1909 and was foundational to the efforts of world war 1. Ammonia has a wide variety of uses including agriculture and mining. It uses le chatelier’s principles to make it possible to produce ammonia at scale.


The Haber Process was developed to help with humanity’s ever growing need for food as the human population grew. As agriculture grew, fertilizer also had to be developed in sufficient quantity to account for the ever increasing demand. Hence Haber developed a process to produce ammonia to be used as a fertilizer.

The Haber Process can be summarized by the below exothermic reaction.

2N2 (g) +  3H2 (g) <–> 2NH3 (g)

By tweaking the conditions, Haber could produce large quantities of ammonia which had previously been considered as unfeasible.

The reaction was largely exothermic, this would mean to push the equilibrium to the right favoring the production of ammonia, the temperature would have to be decreased. However, this would slow the rate of reaction – the best solution for the above two issues was a temperature between 400 and 450 degrees Celsius.

Additionally, to push equilibrium to the right, the pressure was increased. This increase in pressure, however, increases the cost hence a high pressure of 200 atp is used.

The above to modifications increases the yield of ammonia up to 35%.

To further increase ammonia production the NH3 that is produced is condensed hence the reaction never reaches completion – further increasing yield of NH3 .

The rate of reaction is further increased through adding a Fe3O4/K2O catalyst.

The reaction requires hydrogen gas which is obtained through catalytic cracking of hydrocarbons – shipping containers frequently transport fossil fuels hence most NH3 reaction plants are close to the ocean. The nitrogen gas is already present in the atmosphere.


The Haber process equilibrium reaction Nitrogen plus oxygen forms ammonia.


Question 1.

Explain how the haber process optimises the temperature for yield of ammonia? [3 marks]

Question 2.

Evaluate the socio-scientific impact of the haber process and explain how it optimizes the yield of NH3? [8 marks]

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