Nitrogen Chemistry

Nitrogen Chemistry

The Haber Process

  • The Haber Process is an industrial method for the production of ammonia from nitrogen and hydrogen.
  • The reaction is exothermic and reversible, N2(g) + 3H2(g) ⇌ 2NH3(g) + heat.
  • Iron is commonly used as a catalyst to speed up the reaction.
  • The production of ammonia is favoured by high pressure (200 atm) and low temperature (450˚C). However, a compromise temperature is used in order to quicken the rate of reaction.


  • Ammonia produced in the Haber Process is used to manufacture nitrogen-based fertilisers like ammonium nitrate, NH4NO3, and ammonium phosphate, (NH4)3PO4.
  • These fertilisers increase the availability of nitrogen in the soil, which is needed for plant growth.
  • Nitrogen is a component of proteins, nucleic acids, and chlorophyll, all essential to plant health.
  • Overuse of fertilisers can lead to water pollution through eutrophication.

Nitric Acid Production

  • Nitric Acid, HNO3, can be industrially produced by converting ammonia using the Ostwald Process.
  • The process involves the oxidation of ammonia to nitric oxide (NO), which is then further oxidised to nitrogen dioxide (NO2). The nitrogen dioxide is then absorbed in water to produce nitric acid.
  • The production of nitric acid is significant as it is also a key ingredient in fertilisers and explosives.

Nitrogen Oxides and the Environment

  • Nitric oxide (NO) and nitrogen dioxide (NO2), collectively referred to as NOx, are harmful gases produced through combustion in cars and power plants.
  • These gases react with water in the atmosphere to produce acid rain, which can damage buildings and harm ecosystems.
  • NOx gases are also primary pollutants in the formation of ground-level ozone and smog.

Nitrogen Cycle

  • The Nitrogen Cycle is the process by which nitrogen is converted into various chemical forms as it circulates among the atmosphere, terrestrial, and marine ecosystems.
  • Key processes in the nitrogen cycle include nitrogen fixation, nitrification, assimilation, ammonification, and denitrification.
  • Human activities such as the burning of fossil fuels and excessive use of nitrogen-based fertilisers can disrupt the nitrogen cycle, leading to ecological imbalances and environmental problems.