Fertilisers Flashcards
(23 cards)
What are fertilisers?
They provide mineral ions (most importantly: Nitrogen, phosphorous and potassium)
What did farmers used to use as fertilisers?
manure
Why are formulated fertilisers better than manure?
more widely available, easier to us, don’t smell and have just enough of each nutrient so more crops can be grown.
Why are fertilisers needed?
When plants grow they absorb minerals from the water in the soil. Overtime, this can lead to a decrease in the concentration of these ions in the soil, making it more difficult to grow new crops.
What does the use of fertilisers achieve?
the missing elements in the soil are replaced/added to the soil which helps to increase crop yield as the crops can grow bigger and faster
Compounds of nitrogen, phosphorus and potassium are used as fertilisers to improve agricultural productivity.
NPK fertilisers contain compounds of all three elements.
How are NPK fertilisers produced?
Industrial production of NPK fertilisers can be achieved using a variety of raw materials in several integrated processes.
What are NPK fertilisers?
formulations of various salts containing appropriate percentages of the elements.
Fertiliser compounds must be soluble to be absorbed by root hair cells
ammonium ions (NH4+) and nitrate ions (NO3-) are sources of soluble nitrogen. Whilst phosphate ions (PO43-) are a source of soluble phosphorus. All common potassium compounds
dissolve in water to produce potassium ions (K+)
How can nitric acid be produced by using ammonia?
Ammonia can be reacted with oxygen and water in a series of reactions to make nitric acid.
What happens if you react ammonia with acids?
You can react it with acids including nitric acid to get salts that can be used in fertilisers
So what can ammonia be used to manufacture
Ammonium salts and nitric acid
Which salts can be manufactured using ammonia?
.ammonium nitrate (nitric acid)
.ammonium sulphate
.ammonium phosphate
What is the symbol equation for ammonium nitrate?
NH3 + HNO3 → NH4NO3
(all aq)
What 3 things are obtained by mining?
Potassium chloride, potassium sulphate and phosphate rock.
Which 2 sources of potassium can be used directly in fertiliser manufacture?
Potassium chloride and potassium sulphate.
Why can’t phosphate rock be used directly as a fertiliser?
coz the phosphate salts in the rock are insoluble so plants can’t directly absorb them as nutrients
What has to happen to the phosphate rock before it can be used?
Phosphate rock is treated with nitric acid or sulphuric acid to produce soluble salts that can be used as (NPK) fertilisers.
What happens when phosphate rock is reacted with nitric acid?
Phosphoric acid and Calcium nitrate.
What happens when phosphate rock is reacted with sulphuric acid?
Calcium sulphate and calcium phosphate. (this mixture is known as a single super-phosphate)
What happens when phosphate rock is reacted with phosphoric acid?
Calcium phosphate (the production of this reaction can be called triple super-phosphate)
How is the reaction of e.g. ammonium nitrate carried out in industry?
. carried out in giant vats at high concentrations resulting in a very exothermic reaction
.the heat released is used to evaporate water from the mixture to make a very concentrated ammonium nitrate product.
How is the reaction of e.g. ammonium nitrate carried out in the lab?
. carried out on a much smaller scale by titration & crystallisation
.lower concentration so less heat is produced by reaction - safer for a person to carry out
. after titration the mixture needs to be crystallised to give pure ammonium nitrate crystals (crystallisation isn’t used in industry cos it’s very slow)
