Page 1 of 30 Q1. This question is about fertilisers. Some fertilisers are described as NPK fertilisers because they contain three elements needed for healthy plant growth. (a) Which two compounds each contain two of these elements?
Tick (✓) two boxes.
Ammonium nitrate Ammonium phosphate Calcium chloride Calcium phosphate Potassium chloride Potassium nitrate (2) (b) Rocks containing calcium phosphate are treated with acid to produce
soluble salts that can be used as fertilisers.
Name the soluble salts produced when calcium phosphate reacts with:
• nitric acid
• phosphoric acid.
Nitric acid _________________________________________________ Phosphoric acid __________ ____________________________________ (2) (c) Ammonium sulfate is a compound in fertilisers.
Ammonium sulfate can be made using an ind ustrial process or in the
laboratory.
In the industrial process, the following steps are used.
1. React streams of ammonia solution and sulfuric acid together.
2. Evaporate the water by passing the solution down a warm column.AQA Chemistry GCSE - The Haber Process and the Use of NPK Fertilisers Page 2 of 30 3. Collect dry crystals continuously at the bottom of the column.
In the laboratory, the following steps are used. 1. React ammonia solution and sulfuric acid in a conical flask.
2. Evaporate water from the solution until crystals start to form.
3. Leave to cool and crysta llise further.
4. Separate the crystals using filtration.
5. Dry the crystals between pieces of filter paper.
Evaluate the two methods for producing a large mass of ammonium sulfate. ___________________________________________________________ ___________________________________________________________ ______________________________________________________ _____ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ _______________ ____________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ (4) (Total 8 marks) Q2. This question is about ammonia and fertilisers. Ammonia is produced from nitrogen and hydrogen. A catalyst is used to speed up the reaction. The word equation for the reaction is: nitrogen + hydrogen ⇌ ammonia (a) What does the symbol ⇌ show about the reaction?
___________________________________ ________________________
___________________________________________________________AQA Chemistry GCSE - The Haber Process and the Use of NPK Fertilisers Page 3 of 30 (1) (b) Which catalyst is used when ammonia is produced from nitrogen and
hydrogen?
Tick (✓) one box.
Chlorine Iron Oxygen (1) (c) The diagram below shows the reaction profile for the production of
ammonia both with a catalyst and without a catalyst.
What is represented by label X? Tick (✓) one box. Activation energy with a catalyst Activation energy without a catalyst Overall energy change with a catalyst Overall energy change witho ut a catalyst AQA Chemistry GCSE - The Haber Process and the Use of NPK Fertilisers Page 4 of 30 (1) Ammonia is used to produce fertilisers. NPK fertilisers contain the elements nitrogen, phosphorus and potassium. A fertiliser contains: • 22% phosphorus
• 25% potassium.
(d) Draw a bar chart on the graph below to show the percentages of
phosphorus and of potassium in this fertiliser.
(2) (e) Why do the percentages of phosphorus and of potassium in this fertiliser
not add up to 100%?
___________________________________________________________
___________________________________________________________
(1) Fertilisers help plants grow by adding essential elements to soil. The table below shows the percentages of nitrogen, phosphorus and potassium in four fertilisers, A, B, C and D. Fertiliser Percentage (%) of essential element Nitrogen (N) Phosphorus (P) Potassium (K) A 14 0 39 AQA Chemistry GCSE - The Haber Process and the Use of NPK Fertilisers
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