A farmer wants to use ammonium sulfate as a fertiliser on a field of wheat. State what type of compound ammonium sulfate is and explain why the nitrogen it contains is beneficial to the growth of the wheat plants.

Cambridge International IGCSE Chemistry (0620) — 10.2 Fertilisers · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Ammonium sulfate is a salt (an artificial/synthetic fertiliser).

The nitrogen in ammonium sulfate is taken up by the wheat plants and used for the synthesis of proteins. Proteins are essential for cell growth, the formation of new cells and the production of enzymes. Without sufficient nitrogen, plant growth is stunted, leaves turn yellow and overall yield is reduced.

Examiner tips

  • Use the word "salt" and note it is a synthetic fertiliser; this earns the first point. Explain that nitrogen is used for protein synthesis, linking to cell growth and enzyme production. Mention the visual symptom (yellowing leaves) to show the effect of deficiency. Keep the answer concise and use the exact terminology from the mark scheme.

Common mistakes

  • Calling ammonium sulfate a compound but not specifying it is a salt. Forgetting to link nitrogen to protein synthesis. Omitting the consequence of nitrogen deficiency such as stunted growth or yellow leaves.

Mark scheme (4 marks)

  1. Ammonium sulfate is a salt (accept: artificial/synthetic fertiliser)
  2. Nitrogen is needed for the synthesis / production of proteins
  3. Proteins are needed for growth / cell growth / building new cells / making enzymes
  4. Without sufficient nitrogen / fertiliser, plant growth is stunted / poor / leaves turn yellow

Key terms in this question

ammonium sulfate · fertiliser · nitrogen

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