Using Resources Flashcards
What element do most fertilisers contain?
Most fertilisers contain nitrate
What does ‘Fixing nitrogen’ mean?
making the nitrogen in the air soluble
What are the raw products of the Haber process?
nitrogen in the air
hydrogen - mainly from natural gas (has methane)
What are the conditions for the Haber process?
Iron Catalyst
450 degrees celsius
200 Atm
What is the reaction in the Haber process? (unbalanced)
N2+H2 –> NH3
How does the Haber process work?
Ammonia is removed by cooling the gases so that ammonia liquifies and is separated from unreacted N2 and H2 gases –> these are recycled back into the mixture
These gases are re-compressed and heated, and then returned to the reaction vessel
How is Nitrogen obtained? What are the problems of this?
Nitrogen is extracted from the air by fractional distillation of liquid air –> cooling of -200 degrees celsius requires a lot of energy
In cooling process, air must be compressed by high pressure pumps which are expensive to run
How is Hydrogen obtained?
Hydrogen is made by reacting methane with steam
methane + steam –> carbon monoxide + hydrogen
What are the costs of obtaining hydrogen for the Haber process?
Water is cheap, but the heat requires energy
Methane costs are the main one in the Haber process as it must be bought from the gas and natural gas industry
How does a catalyst affect the reaction?
A catalyst does not lead to greater yield of ammonia, but speeds up the process
How is Ammonia reacted to produce different salt fertilisers?
- nitric acid –> ammonium nitrate
- sulfuric acid –> ammonium sulfate
- phosphoric acid –> ammonium phosphate
These reactions are all neutralisation reactions as ammonia is an alkali
What is NPK?
Nitrogen, Phosphorus and potassium are the ‘macro nutrients’
What is the source of phosphorous?
the sources of phosphate are deposits of phosphate-containing rock –> insoluble in water and is not used directly
What is the Phosphate rock treatment?
Phosphate rock treatment:
1. reacted with nitric scid and phosphoric acid (H3PO4) –> which is then neutralised with ammonia to give ammonium phosphate
ammonium phosphate is reacted with sulfuric to give supersingle phosphate - a mixture of calcium phosphate and calcium sulfate
this is reacted with phosphoric acid to give triple superphosphate - calcium phosphate
The potassium salts KCl and Potassium sulfate are mined from the group
What are the conditions needed to make fertilisers in the industry?
- giant vats
- High concentrations
- Very exothermic –> released energy is used to evaporate water released from the mixture
- very concentrated ammonium nitrate produced
