AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
Ammonia can be used to manufacture ammonium salts and nitric acid.
Full specification wording
Production and uses of NPK fertilisers: Ammonia can be used to manufacture ammonium salts and nitric acid.
Ammonia is a versatile starting material because it is a base and a source of nitrogen.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 5 of 8
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Ammonia is a versatile starting material because it is a base and a source of nitrogen. Reacting ammonia with an acid produces an ammonium salt in a neutralisation reaction: ammonia plus nitric acid gives ammonium nitrate, ammonia plus sulfuric acid gives ammonium sulfate, and ammonia plus phosphoric acid gives ammonium phosphate. These salts are water-soluble and supply nitrogen, and in some cases phosphorus, to plants. Ammonia is also oxidised industrially, typically over a heated catalyst, to nitrogen monoxide, which is further oxidised to nitrogen dioxide and dissolved in water to make nitric acid. That nitric acid can then be reacted with more ammonia to make ammonium nitrate, so the two products are linked within an integrated fertiliser process.
What earns the marks
- States that ammonia reacts with acids in neutralisation to form ammonium salts.
- Gives named examples such as ammonium nitrate, ammonium sulfate or ammonium phosphate with the acid used.
- Describes the industrial oxidation of ammonia to nitrogen monoxide and then nitrogen dioxide.
- Explains that nitrogen dioxide reacts with water to produce nitric acid.
- Links the nitric acid produced back to ammonium nitrate manufacture in an integrated process.
Common mistakes and how to put them right
Writing that ammonia plus acid produces a metal salt.
Put it right by naming an ammonium salt such as ammonium nitrate.
Confusing the oxidation route to nitric acid with neutralisation.
Put it right by separating the catalytic oxidation steps from the acid–base reaction.
Omitting water from the formation of nitric acid.
Put it right by stating that nitrogen dioxide is absorbed in water.
Exam tips
- For each ammonium salt, name the acid that supplies the anion.
- Sequence the nitric acid route clearly: ammonia to nitrogen monoxide, to nitrogen dioxide, then to nitric acid.
- Use balanced equations where asked, and check that ammonium ions carry a 1⁺ charge.
Try the lesson
The start of the Production and uses of NPK fertilisers: Ammonia can be used to manufacture ammonium salts and nitric acid. lesson, made from checked teaching notes for this specification point.
Have a go first
Which two important chemical products can be manufactured directly or indirectly from ammonia?
Listen
Ammonia is a versatile starting material because it is a base and a source of nitrogen. Reacting ammonia with an acid produces an ammonium salt in a neutralisation reaction: ammonia plus nitric acid gives ammonium nitrate, ammonia plus sulfuric acid gives ammonium sulfate, and ammonia plus phosphoric acid gives ammonium phosphate. These salts are water-soluble and supply nitrogen, and in some cases phosphorus, to plants. Ammonia is also oxidised industrially, typically over a heated catalyst, to nitrogen monoxide, which is further oxidised to nitrogen dioxide and dissolved in water to make nitric acid. That nitric acid can then be reacted with more ammonia to make ammonium nitrate, so the two products are linked within an integrated fertiliser process. A strong answer earns marks for these points. States that ammonia reacts with acids in neutralisation to form ammonium salts. Gives named examples such as ammonium nitrate, ammonium sulfate or ammonium phosphate with the acid used. Describes the industrial oxidation of ammonia to nitrogen monoxide and then nitrogen dioxide. Explains that nitrogen dioxide reacts with water to produce nitric acid. A common slip: Writing that ammonia plus acid produces a metal salt. Instead, naming an ammonium salt such as ammonium nitrate. Exam tip: For each ammonium salt, name the acid that supplies the anion.
Key words
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Neutralisation and salt formation
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Ammonia as a feedstock
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Catalytic oxidation
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Integrated industrial chemistry
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See every definition
- Neutralisation and salt formation
- Reacting ammonia with an acid produces an ammonium salt in a neutralisation reaction, and these salts are water-soluble and supply nitrogen to plants.
- Ammonia as a feedstock
- A versatile starting material because it is a base and a source of nitrogen, used to manufacture ammonium salts and nitric acid.
- Catalytic oxidation
- Ammonia is oxidised industrially, typically over a heated catalyst, to nitrogen monoxide, which is further oxidised to nitrogen dioxide and dissolved in water to make nitric acid.
- Integrated industrial chemistry
- The nitric acid produced can then be reacted with more ammonia to make ammonium nitrate, so the two products are linked within an integrated fertiliser process.
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