The Haber Process
- Created by: Jo Wells
- Created on: 20-04-13 13:07
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- The Haber Process
- nitrogen & hydrogen make ammonia
- N2 + 3H2 <-> 2NH3 (+heat)
- nitrogen obtained from air - 78% nitrogen
- hydrogen from natural gas/other sources like crude oil
- gases are first purified
- nitrogen obtained from air - 78% nitrogen
- gases are first purified
- some of the nitrogen reacts with the hydrogen to form ammonia - as reaction is reversible it goes both ways
- the ammonia itself breaks down back into the nitrogen and hydrogen
- industrial contitions
- 200 atmospheres of pressure
- 450 degrees C
- iron catalyst
- compromise
- higher pressures favour the forward reaction (fewer molecules on the right side)
- so pressure is set as high as possible to give the best % yield, without being too expensive
- forward reaction is exothermic, so would work better with a lower temperature
- but lower temperatures mean a lower rate of reaction - have to increase the temperature to get a faster rate
- 450 degrees C is a compromise between maximum yield & speed of reaction
- better to wait 20 secs for 10% than 60 secs for 20%
- 450 degrees C is a compromise between maximum yield & speed of reaction
- but lower temperatures mean a lower rate of reaction - have to increase the temperature to get a faster rate
- higher pressures favour the forward reaction (fewer molecules on the right side)
- iron catalyst speeds up reaction & keeps costs down
- makes reaction go faster - gets to equilibrium proportions faster, without affecting the position of equilibrium
- without catalyst the temperature would need to be raised even higher to make reaction fast enough - reduce % yield even more
- nitrogen & hydrogen make ammonia
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