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Ammonia

Terms in this set (31)

The Haber process is a method used to make ammonia directly from ___ and ___
nitrogen and hydrogen
The nitrogen is obtained from ____
fractional distillation of liquefied air
The hydrogen is derived mainly from ____
natural gas and water in steam reforming
Steam reforming
The combination of nitrogen and hydrogen into ammonia is a ____ reaction. The forward reaction is ___ and results in a decrease in volume
reversible, exothermic
Combination of nitrogen and hydrogen
What does Le Chatelier's Principle state about the Haber Process?
- the reaction is exothermic and results in a decrease in volume
- therefore, low temp and high pressure would shift equilibrium to the right and increase the ammonia yield
Contradictions with Le Chatelier's Principle and Haber Process
- at low temps the reaction rate would be too slow to be economical
- at high pressures the cost & maintenance of equipment would be very expensive
For commercial production a compromised temperature of about ___ is used with a catalyst
450oC
The conditions of the Haber Process will produce a yield of about ___ ammonia at an acceptable rate
10%
Economical production of ammonia
It is more economical to produce a lower yield of ammonia is a short time rather than wait several years for the equilibrium mixture to reach a very high yield
The catalyst is usually ___ mixed with small amounts of promoters such as ___ and ___
iron, potassium oxide and aluminium oxide
The promoters increase the ___ of the catalyst
efficiency
Purification of both the nitrogen and hydrogen gases is necessary to prevent ___ of the catalyst
'poisoning'
Economical pressure considerations
- increased pressure increases ammonia yield and rate of reaction
- reaction is usually carried out at pressures ranging 200-400 atm
- cost of producing ammonia at very high pressure is very expensive and may not be worth further increase in yield of ammonia
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