Worksheet
Total marks:
/45
1. Group the following substances into natural and synthetic fertilisers.
Ammonia
Ammonium salts
Animal manure
Dead animals
Food leftovers
Human pee and poo
Nitrates
NPK fertilisers
Phosphates
Plant compost
Natural fertilisers
Synthetic fertilisers
/ 10 marks
2. Match the name with the correct chemical formula.
Hydrogen gas
NH3 (g)
Nitrogen gas
NH3 (l)
Ammonia gas
N2 (g)
Liquid ammonia
H2 (g)
/ 4 marks
5
3. Write the following equations for the reversible reaction of hydrogen and
nitrogen to make ammonia.
a. Word equation
/ 2 marks
b. Imbalanced chemical equation
/ 2 marks
c. Balanced chemical equation
/ 4 marks
4. Fill the gaps with the words from the box.
200
Haber
450
compound
hydrogen
iron
element
rate
Nitrogen is an important __________________ which is needed for plants to grow.
Plants can absorb nitrogen from the ____________________ammonia. Most
ammonia is made by the _____________________ process. In this process a
reversible reaction between nitrogen and _____________________ is used to
produce ammonia. An _____________________ catalyst is used to increase the
_____________________ of the reaction. The reaction is exothermic, so a
moderate temperature of ______________________ °C is used. This gives a
reasonable yield of ammonia at a reasonable rate. A pressure of
____________________ atmospheres is used to give a good yield of ammonia.
/ 8 marks
6
5. Match each problem with its solution.
Problems
1. Crops remove nutrients from the
soil.
Solutions
A. Iron catalyst is used to increase the
rate of the reaction in the Haber
Process.
B. Fertilisers are used to restore the
elements essential for plant growth.
2. Plants cannot break down the
nitrogen from the air as it contains
strong triple bonds.
3. Natural fertilisers are not effective
C. A moderate pressure of 200
enough and there often isn't enough atmospheres is used to maximise the
to cover large fields.
yield of ammonia while minimising
the costs.
4. The rate of Haber Process is not D. Ammonia contains nitrogen
high enough.
which can be absorbed by the
plants.
5. It is difficult to separate gaseous E. The product mixture is cooled
ammonia from unreacted hydrogen down so that ammonia becomes a
and nitrogen which are also gaseous. liquid and can be easily separated.
6. The reaction is reversible so a F. Moderate temperature of about
significant amount of hydrogen and 450 degrees is used.
nitrogen remains unreacted after the
process.
7. At low temperatures, the rate of
G. Synthetic fertilisers are used to
the reaction is too slow. At high
help crops grow larger and faster on
temperatures, the yield of the
a large scale.
reaction is too low.
8. At high pressure, the production of H. Unreacted hydrogen and nitrogen
ammonia is favoured. But high can be recycled to reduce the costs
pressure is very expensive to achieve. and minimise the waste.
Problem 1
Solution _____
Problem 2
Solution _____
Problem 3
Solution _____
Problem 4
Solution _____
Problem 5
Solution _____
Problem 6
Solution _____
Problem 7
Solution _____
Problem 8
Solution _____
/ 8 marks
7
6. Order the following sentences by annotating the eutrophication timeline
with the appropriate letters.
A - The fish suffocate and die.
B - The dead and decaying plants prevent new plants from accessing sunlight.
C - Aerobic bacteria grow and multiply as they consume the dead plants.
D - Synthetic fertilisers are washed into rivers and lochs.
E - The aquatic plants are not eaten by humans so they just die and decay.
F - The oxygen levels in the water drop.
G - The more aerobic bacteria, the more oxygen they consume.
H - The fertilisers cause the aquatic plants to grow faster and larger.
I - The new plants cannot photosynthesise so they also die and decay.
Cause
Effect
A
D
/ 7 marks
8