AQA GCSE Chemistry (8462), Higher tier · Using resources › The Haber process and NPK fertilisers
Practise Production and uses of NPK fertilisers. 15 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Ammonia is used to manufacture ammonium salts and nitric acid. Name the salt formed when ammonia reacts with nitric acid.
ammonium nitrate
Name the salt formed when phosphate rock is treated with phosphoric acid.
calcium phosphate
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
(a) Name the three elements that NPK fertilisers provide.[1]
(b) Why do farmers use fertilisers?[1]
(c) Which substance is obtained by mining and is used as a source of potassium in fertilisers? Tick (✓) one box.[1]
Ammonium nitrate
Nitric acid
Phosphoric acid
Potassium chloride
(d) NPK fertilisers are formulations. What does this mean?[1]
Show the answer and mark scheme
(a)
nitrogen, phosphorus and potassium (all three needed)
(b)
to improve agricultural productivity / to increase crop yields
(c)Answer: Potassium chloride
(d)
they are mixtures of different salts containing the elements in appropriate percentages / designed as useful products
Question 2Medium5 marks
Ammonia is used to manufacture ammonium salts and nitric acid.
(a) Name the salt formed when ammonia reacts with nitric acid.[1]
(b) Balance the equation for the production of ammonium sulfate. ....NH3 + H2SO4 → (NH4)2SO4[1]
(c) Name the acid that reacts with ammonia to produce ammonium phosphate.[1]
(d) A fertiliser factory has an ammonia plant and a nitric acid plant on the same site. Suggest two advantages of this.[2]
Show the answer and mark scheme
(a)Answer: ammonium nitrate
ammonium nitrate
(b)Answer: 2NH3 + H2SO4 → (NH4)2SO4
2 (NH3)
(c)Answer: phosphoric acid
phosphoric acid
(d)
ammonia is needed to make nitric acid
the nitric acid can then be reacted with more ammonia to make ammonium nitrate
no transport costs / less transport between sites
energy released by one process can be used in another (integrated processes)
Question 3Hard4 marks
A farmer is deciding whether to use manure, an organic fertiliser made from animal waste, or a manufactured NPK fertiliser.
Evaluate the use of manure compared with manufactured NPK fertiliser.[4]
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manure recycles nutrients from animal waste, a by-product, rather than using new raw materials and energy in a manufacturing process, so it can be cheaper and more sustainable if available locally
manure has a variable, generally less precisely known nutrient content, so it is harder to apply the exact amount of each nutrient a crop needs
manufactured NPK fertiliser has a precisely known, controllable composition, so farmers can apply exactly the nutrients needed, but manufacturing it, e.g. via the Haber process, uses significant energy and finite resources such as mined phosphate rock
many farmers use a combination of both, using manure where available and manufactured fertiliser to make up any shortfall precisely