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chemistry igcse acapprinted 72 · PDF 72
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odors. The final step is chlorination. Since bacteria and other microorganisms are too small to be
captured by filters, chlorine is added to the water supply to kill them. Diseases like cholera and
typhoid can result from consuming untreated water containing harmful bacteria.
Fertilizers
NPK fertilizers are crucial for enhancing plant growth and health by supplying key nutrients:
Nitrogen (N): Essential for producing chlorophyll and proteins, it helps plants grow healthy, green
leaves. Nitrogen is provided through ammonium ions (NH₄⁺) and nitrate ions (NO₃⁻).
Phosphorus (P): Aids in the development of strong roots, improving the plant's stability and
nutrient absorption. It is available as phosphate ions (PO₄³⁻).
Potassium (K): Encourages the growth of robust fruit, flowers, and overall plant health. It dissolves
in water as potassium ions (K⁺).
Common fertilizer compounds include:
Ammonium nitrate (NH₄NO₃)
Ammonium phosphate ((NH₄)₃PO₄)
Potassium nitrate (KNO₃)