Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

10.2Chemistry of the Environment

Fertilisers — Cambridge IGCSE Chemistry 0620 Revision Notes & Topical Questions

5 min read 7 parts Lesson 2 of 4 1 quiz

📚 Cambridge IGCSE Chemistry 0620 Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
0%read
Lesson summary

10.2 Fertilisers — IGCSE CHEMISTRY notes: State that ammonium salts and nitrates are used as fertilisers and describe the use of NPK fertilisers.Fertilisers — ammonium salts and nitrate salts are commonly used.Examples — ammonium nitrate, NH4NO3, ammonium phosphate, (NH4)3PO4, an…

  • Water-soluble ions
  • Proportions
  • Choosing the most effective
  • Percentage of nitrogen
  • Washing in
  • Algal bloom

Part 1 of 5Fertilisers and compounds used

Fertilisers
  • Fertilisers ammonium salts and nitrate salts are commonly used.
Examples
  • Examples ammonium nitrate, NH4NO3, ammonium phosphate, (NH4)3PO4, and potassium nitrate, KNO3.
Purpose
  • Purpose they provide the elements plants need for improved growth.

Part 2 of 5NPK fertilisers

ElementRole in the plantSoluble ion absorbed
NitrogenMakes chlorophyll and protein; healthy leavesNH4+, NO3-
PhosphorusHealthy rootsPO43-
PotassiumGrowth; healthy fruit and flowersK+
  • Water-soluble ions
    • fertiliser compounds contain ions that dissolve in water.

Part 3 of 5Different fertilisers

Different fertilisers
Proportions
  • Proportions different fertilisers contain different proportions of nitrogen, phosphorus and potassium.
Choosing the most effective
  • Choosing the most effective select the compound or combination containing the most of the elements N, P and K.
Percentage of nitrogen
  • Percentage of nitrogen ammonium nitrate contains 35% nitrogen.

Part 4 of 5Environmental effect

Washing in
  • Washing in excess nitrates and phosphates from fertilisers wash into rivers and lakes.
Algal bloom
  • Algal bloom algae grow rapidly and cover the surface, blocking light from plants below.
Deoxygenation
  • Deoxygenation bacteria decomposing the dead plants and algae use up dissolved oxygen.
Result
  • Result fish and other aquatic organisms die (eutrophication).

Part 5 of 5More from the specification

1
Ammonium phosphate salts and transitional metal
  • Ammonium phosphate salts and transitional metal neutralising phosphoric acid with ammonia produces soluble fertilisers,
    • while trace transition metal ions prevent plant chlorosis.
2
Essential Macronutrients in NPK Fertilisers
  • Commercial NPK synthetic fertilisers provide nitrogen, phosphorus (stimulating root development), and potassium (improving flower and fruit yields).
    • (promoting healthy leaf and foliage growth)
3
Industrial Synthesis of Ammonium Salts
  • Neutralising aqueous ammonia with nitric acid or sulfuric acid generates soluble nitrogenous fertilisers: NH3 + HNO3 → NH4NO3 and 2NH3 + H2SO4 → (NH4)2SO4 (ammonium sulfate).
    • (ammonium nitrate)
4
Multi-Stage Municipal Water Treatment
  • Potable water production incorporates coarse sedimentation, filtration through sand beds to remove insoluble particulates,
    • and controlled chlorination to eliminate microbial pathogens.
5
Melting
  • Solid to liquid at the melting point, absorbing energy.
6
Distilled water
  • Water made by boiling and condensing to remove dissolved impurities.
7
Substance
  • A material with only one type of particle.
8
Impurity
  • Unwanted substance in a product.
9
Anhydrous
  • Containing no water of crystallisation.
10
Sulfate
  • Salt of sulfuric acid.
11
Hydrated
  • Containing water of crystallisation.
12
Temperature
  • A measure of the average kinetic energy of the particles.
13
Boiling
  • Liquid to gas throughout the liquid at the boiling point.

Key terms

TermMeaning
FertiliserA substance added to soil to supply plant nutrients.
NPK fertiliserContains nitrogen, phosphorus and potassium.
Ammonium nitrateNH4NO3, a fertiliser with 35% nitrogen.
EutrophicationExcess nitrates and phosphates cause algal blooms and oxygen depletion.
Nitrate ionNO3-, a soluble source of nitrogen for plants.

Avoid these mistakes

1
Saying fertilisers poison the fish — nitrates cause algal growth and decomposing bacteria use up the dissolved oxygen.
2
Forgetting that fertiliser compounds must be soluble to be absorbed by roots.
3
Saying NPK stands for nitrogen, protein and potassium — it is nitrogen, phosphorus and potassium.
4
Choosing a fertiliser with only one of the three elements when asked for the most effective — choose the one with the most of N, P and K.

Last updated: