C6.1.1 Fertilsers

Question 1

Fertilisers

Answer 1

Substances that replace the elements used by plants as they grow.

Question 2

Elements + deficiency

Answer 2

Nitrogen N - poor growth, yellow leaves
Phosphorus P - poor root growth
Potassium K - poor fruit growth, discoloured leaves

Question 3

Eutrophication

Answer 3

• Type of water pollution caused by the addition of fertilisers.
• The fertilisers run-off increasing the nitrate concentration of the water + has a - effect on aquatic ecosystem

Question 4

Eutrophication stages

Answer 4

• excess nutrients enter water
• nutrients promote plant growth mainly algae
• algae blooms occur
• algae dies and is decomposed by bacteria
• decomposition of algae increases biological oxygen demand
• oxygen levels decrease
• fish + other aquatic life dies = no O2

Question 5

Ammonia used to produce nitrogen-containing compounds

Answer 5

1) ammonia reacted O2 + H2O in series of reactions = HNO3
2) ammonia + nitric acid —> ammonium salts - used as fertilisers
3) ammonia + nitric acid —> ammonium nitrate = good compound to use in fertilisers as it has nitrogen from 2 sources

Question 6

Fertilisers in industry

Answer 6

1) reaction carried out in giant vaults @ high concs = very endothermic reactions
2) heat released used to evaporate H2O from the mixture make a very conc ammonium nitrate product

Question 7

Fertilisers in lab

Answer 7

1) reaction carried out smaller scale = titration + crystallisation
2) reactants are a much lower conc than in industry so less heat produced by reaction + safer for person to carry out
3) after titration mixture needs to be crystallised to give pure ammonium nitrate crystals
4) crystallisation isn’t used in industry because it is v slow

Question 8

Phosphate + Potassium sourced from mined compounds

Answer 8

1) potassium chloride + potassium sulphate mined + used as a source of potassium
2) phosphate rock also mined. HOWEVER because phosphate salts in rock are insoluble plants can’t directly absorb them + use as nutrients
3) reacting phosphate rock w number of diff types of acids produces soluble phosphates:
Reaction nitric acid —> phosphoric acid + calcium nitrate
Reaction w sulfuric acid —> calcium sulfate + calcium phosphate = single superphosphate
Reaction w phosphoric acid only produces calcium phosphate = triple superphosphate