FERTILISERS
Why? How? How long? Advantages? Disadvantages?
Why do we use fertilisers and how long have they been around?
How do we make them?
Advantages and Disadvantages
What is the Haber Process?
The Haber Process is an important industrial process that produces ammonia, a substance that is needed for making fertilisers. Nitrogen and Hydrogen are needed to make ammonia. The nitrogen is easily extracted from the air and hydrogen is obtained from natural gas. The reaction is reversible so not all of the nitrogen and hydrogen will react. The reaction reaches a dynamic equilibrium.
The industrial manufacture of ammonia uses the following conditions:
Pressure: 200 atmospheres
Temperature: 450 degrees C
Catalyst: Iron
The pressure is set as high as possible to give the best percentage yield without making the plant too costly to build and run.
The reaction is exothermic so the increasing of temperatures will reverse the reaction and cause ammonia to break down into H2 and N2. Lower temperatures mean a greater yield of ammonia. Lowering the temperatures lower the rate of reaction so the temperature is raised to get a faster reaction.
The ammonia is formed as a gas but the condenser cools it, liquifying it and then it is removed.
The iron is only a catalyst. It makes the reaction go faster but it doesn't affect the percentage yield.