C15.5 - C15.8 - Using Our Recources (Set A)✔️ Flashcards
Word equation for reaction to form ammonia?
Nitrogen + hydrogen — iron catalyst —ammonia
What does the Harber process provide?
Harber process provides a way of turning nitrogen in the air into ammonia which is usefull for making fertiliser - process named after German chemist ( Fritz Haber)
What are the raw material for the production of ammonia?
-nitrogen from the air
-hydrogen - mainly from natural gas
How is the ammonia removed during the harber process?
Removed by cooling the gases so that the ammonia liquefies it can then be seperated from the unreactive nitrogen and hydrogen gas
What does it mean the reaction used in the harber process is reversible?
The ammonia gas made breaks down again into nitrogen and hydrogen
Which conditions are the harber process carried out in?
-450 degrees
-200 atmospheres pressure
-using an iron catalyst
What would a low temperature result in for the reaction to from ammonia?
Slower rate of reaction (and so equalibrium is reached more slowly) higher yeild of ammonia
What would a high temperature result in for the reaction to from ammonia?
The forward reaction in the haber process is exothermic so increasing the temperature will move equalibrium the wrong way away from ammonia and towards nitrogen and hydrogen - decreasing the ammonia produced
Which pressure would we use for the haber process?
Higher pressure moves the position of equalibrium towards the products and increases the precentage yeild and increases rate or reaction
Why is 450 degrees used for the haber process?
It is a compromise between maxium yeild and speed of reaction so it is more economical
Why is 200 atmospheric pressure used for haber process?
Pressure is set as high as possible without making the process to expensive as it would require advanced machinery
Why is an iron catalysts used in the haber process?
Speeds up the rate of both the forward and reverse reactions by the same amount but does not effect the actual yeild of ammonia produced but decreases time it takes so it is more economical
How is the needed nitrogen gas for the haber process obtained?
Nitrogen gas needed extracted from the air
How is the needed hydorgen gas for the haber process obtained?
Made by reacting methane gas with steam at very high temperatures
Methane + steam - hydrogen + carbon monixide
Issues with the hydrogen being made for the haber process?
- Costs involved in heating the reaction mixture to make super-heated steam
- Price of metahane gas which has to be brought from the gas industry
Whta happens to most of the ammonia formend in the haber process?
- Most is changed into compounds of ammonia
- 10% of ammonia made is converted into nitric acid through another process which can then be reacted with more amonia to make ammonium nitrate fertiliser
Word equation for the reaction to form ammonium nitrate?
Ammonia + nitric acid - ammonium nitrate
How can we make other fertiliser with the ammonia produced through the haber process?Three examples?
Other solid fertiliser salts made by reacting ammonia (alkali) with different acids:
- ammonium nitrate
- ammonium phosphate
- ammonium sulfate
Word equation for the neutralisation reaction between ammonia solution and phosphoric acid?
Ammonia + phosphoric acid - ammonium phosphate
Word equation for the neutralisation reaction between ammonia solution and sulfuric acid?
Ammonia + sulfuric adid - ammonium sulfate
Word equation for the reaction of making hydrogen for the haber process?
Methane + steam - hydrogen + carbon monixide
Symbol equation for reaction to make ammonia?
N₂(g) + 3H₂(g) - 2NH₃(g)
How is the ammonia made via the haber process seperated?
Ammonia seperated by cooling the gas so that it liquifies
What happens to the unreactive hydrogen and nitrogen druing the haber process?
Unreactive nitrogen and hydrogen recycled back into the reaction mixture - they are then re compressed and heated before being returned to the reaction vessel
Symbol equation for the reaction to form ammonium nitrate?
NH₃(aq) + HNO₃(aq) - NH₄NO₃(aq)
Symbol equation for the neutralisation reaction between ammonia solution and phosphoric acid?
3NH₃(aq) + HPO₄(aq) - (NH₄)₃PO₄(aq)
Symbol equation for the neutralisation reaction between ammonia solution and sulfuric acid?
2NH₃(aq) + H₂SO₄(aq) - (NH₄)₂SO₄(aq)
What are NPK fertelisers
Fertelisers used to supply nitrogen (N) phosphorus (P) and pottassium (K) to plant - can be added to the land at the same time in mixtures of compounds called NPK ferteliser
Why are NPK fertelisers used on crops?
They increase crop yeild and growth
What are the two sources of most of the salts in NPK fertelisers?
-some are mined
-most made by reacting acids with bases
Why can phosphate rock not be used as a ferteliser?
It can not be used directly on the soil as it is insoluble in water so the rock is treated with acids to make ferteliser salts
Where does pottasium come from for making NPK fertelisers?
Potassium comes from potassium salts mined from the ground for use as fertelisers such as potassium chloride and potassium sulfate
Where does the nitrogen come from for making NPK fertelisers?
Comes from ammonium made in the haber process which is reacted with acids to make fertelisers such as ammonium nitrate and ammonium sulfate
Where does phosphorus come from for making NPK fertelisers?
Source of phosphorus is phosphate rock which is mined and treated with acids to orm fertelisers such as ammonium phosphate
