Topic 10 - Using Resources (NPK fertilisers) Flashcards
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What do farmers use manure for?
to fertilise fields
Why are formulated fertilisers better than manure? (4)
- more widely availiable
- easier to use
- don’t smell
-contain appropriate percentages of element (or nutrient) so crops can be grown
What are the three main essential elements in fertilisers for improving agricultural productivity?
- nitrogen
- potassium
- phosphorus
What happens if plants don’t get enough of the three essential elements?
Their growth and life processess will be affected`
Why may the three main elements be missing from soil?
they could have been used up by a previous crop
When placed into the soil what do fertilisers do? What is the benefit of this (what do they do to plant proteins)?
- replace missing elements or provide more of them
- helps increase crop yield (the crops will grow faster and be bigger)
For example, fertilisers add more nitrogen to plant proteins - which makes them grow faster - increasing agricultural productivity
What are NPK fertilisers?
formulated fertilisers containing salts (compounds) of all three essential elements (nitrogen, phosphorus and potassium) in the appropriate percentages
What things is ammonia used to produce? (2)
2 nitrogen containing products:
- ammonium salts
- nitric acid
What is ammonia reacted with to make nitric acid?
oxygen and water in a series of reactions
What do you produce when you react ammonium with acids?
ammonium salts
What do you get when you react ammonia and nitric acid together?
Why is this a good compound to use in a fertiliser?
- ammonium nitrate
- it has nitrogen from two sources
How may ammmonium nitrate be produced IN INDUSTRY?
- the reation is carried out in giant vats at high concentrations (very exothermic rection)
- heat released is used to evaporate water from the mixture to make a very concentrated ammonium nitrate product
How is industrial production of NPK fertilisers achieved?
using a variety of raw materials in several integrated processes
How may ammonium nitrate be produced in the lab?
- reaction carred out on much smaller scale than in industry by titration and crystallisation
- reactants at lower concentration than in industry (less heat produced by reaction making it safer)
- after the titration the mixture needs to be crystalised to give pure ammonium nitrate crystals
Why isn’t crystallisation used in industry?
It is very slow
Suggest 2 sources of potassium for an NPK fertiliser?
potassium chloride
potassium sulfate
How are potassium chloride and potassium sulphate obtained?
they are obtained by mining
What can be mined as a source of phophorus in NPK fertilisers?
Phosphate rock
Why can’t phosphate rock be used directly as a ferliliser?
the phosphate salts in the rock are insoluble so plants can’t use them as nutrients
Why is phosphate rock treated with nitric or sulfuric acid?
to produce soluble salts (phosphates) that can be used as fertilisers
How can phoshate rock be used as a fertiliser?
- it is reacted (treated) with acid (sulfuric or nitric) to produce soluble salts that can be used as fertilisers
What do you produce when you react phosphate rock with nitric acid?
- phosphoric acid
- calcium nitrate
What do you get when you react phosphate rock with sulfuric acid?
What is this also known as?
- calcium sulfate
- calcium phosphate
(this mixture is known as single superphosphate)
What do you get when you react phosphate rock with phosphoric acid?
What is this also known as?
the reaction only produces calcium phosphate (this product can be called triple superphosphate)
