4.10.4 Haber process and NPK fertilisers (will come up) Flashcards
Outline the key points of Haber process
Include the use of the product
The purified H2 and N2 gases are passed over Fe catalyst at a high temp (450) and a high pressure (200 atm)
Fe speeds up the rate of reaction, so that a lower temperature could be used in the process
Some of the hydrogen and nitrogen reacts to form ammonia
The reaction is reversible so ammonia breaks down again into nitrogen and hydrogen
On cooling, the ammonia liquifies and is removed. The remaining hydrogen and nitrogen are recycled. This means almost no material is wasted
Ammonia is used for production of nitrogen-containing fertilisers
The Haber process operates at high T, p conditions
Explain why this is so and why this is a compromise
The conditions are an optimise between the rate and the yield
The reaction is exothermic. An optimum temp of 450 C is used. Using a lower temperature would give a higher yield but the rate of NH3 production would be too slow
A pressure of 200 atm is used. Using a higher pressure would give a higher yield but would be too expensive because of the cost of energy to produce the high pressure
How are compounds of nitrogen, phosphorus and potassium used
Compounds of nitrogen, phosphorus and potassium are used as fertilisers to improve agricultural productivity.
NPK fertilisers contain compounds of all 3 elements
How is industrial production of NPK fertilisers achieved
Ammonia can be used to manufacture ammonium salts
The ammonium sulfate, phosphate and nitrate can be produced by reaction of ammonia with the requisite acid
How is the phosphate rock utilised in the production of fertilisers
Phosphate rock is reacted with nitric acid to produce phosphoric acid and calcium nitrate
Phosphate rock can be reacted with sulfuric acid to produce a mixture of calcium phosphate and calcium sulfate
Phosphate rock can be reacted with phosphoric acid to produce calcium phosphate
