Chemistry (AS Level)·Nitrogen and Sulfur · NSSCAS 3.5.1
Nitrogen & Ammonia
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Nitrogen is nearly 80% of the air, yet almost nothing reacts with it. Learn why — the very strong N≡N triple bond — and why that forces us to manufacture ammonia. Meet ammonia as a base whose lone pair accepts a proton to make the ammonium ion through a dative bond, displace ammonia from its salts, follow nitrogen's changing oxidation numbers through the nitrogen cycle, and see how fertilisers feed crops but can leach into our water and boreholes.
What you'll learn in this lesson
By the end you should be able to (NSSCAS Chemistry (AS Level) 3.5.1):
- Explain the basicity of ammonia in terms of the lone pair on nitrogen accepting a proton
- Describe the structure of the ammonium ion NH₄⁺ and its formation by an acid–base reaction using a dative (coordinate) bond
- Describe the displacement of ammonia from its salts by warming with a base/alkali
- Comment on the depletion of nitrogen, phosphorus and potassium (N, P, K) from soils by leaching and farming
- Explain the lack of reactivity of nitrogen (strong N≡N triple bond) and the resulting need to manufacture ammonia and its salts as fertilisers
- Describe the changes in oxidation number of nitrogen in the nitrogen cycle: NH₃ (−3), N₂ (0), N₂O (+1), NO₃⁻ (+5)
- State the industrial importance of ammonia and ammonium salts as fertilisers
- Explain the environmental consequences of soluble synthetic nitrate fertilisers: leaching, eutrophication and contamination of drinking water including boreholes
- Suggest the benefits of organic fertilisers in terms of their lower solubility
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