Chemical Industry

The fertiliser industry (N, P, K)

• List, for plants:
  • Three non-mineral nutrients C, H and O and their sources, i.e. the atmosphere (CO₂ ) and rain (H₂O)
  • Three primary nutrients N, P and K and their sources
• Explain why fertilisers are needed.
• Explain the function of N, P and K in plants.
• Interpret the N : P : K fertiliser ratio and perform calculations based on the ratio.
• Describe, explain, write balanced equations and interpret flow diagrams of the following processes in the industrial manufacture of fertilisers:
  • N₂ – fractional distillation of air
  • H₂ – at SASOL from coal and steam
  • NH₃ – Haber process
  • HNO₃ – Ostwald process
  • H₂SO₄ – Contact process
  • NH₄NO₃; (NH₄)₂SO₄
• Evaluate the use of inorganic fertilisers on humans and the environment.
• Define eutrophication as the process by which an ecosystem, e.g. a river or dam, becomes enriched with inorganic plant nutrients, especially phosphorus and nitrogen, resulting in excessive plant growth. As plant growth becomes excessive, the amount of dead and decaying plant material increases rapidly.
• Discuss alternatives to inorganic fertilisers as used by some communities.