Chemistry C3 4.9 The economics of the Haber process.

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What pressure does the Haber process use and why?
The Haber process uses a pressure of around 200 atmospheres to increase the amount of ammonia produced.
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Why aren't higher pressures used in the Haber process?
Although higher pressures would produce more ammonia, they would make the chemical plant too expensive to build and run.
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What temperature is used in the Haber process and why?
A temperature of about 450°C is used for the reaction, although lower temperature would increase the yield of ammonia it would be produced too slowly.
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Why is a pressure of about 200 atmospheres used as an optimum pressure for the Haber process?
It is a compromise between costs and yield. The higher the pressure the greater the yield but more energy is needed to compress the gas and stronger reaction vessels and pipes to withstand the increased pressure, therefore costs also increase.
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The higher the pressure the greater the yield of ammonia, why is this?
The products have fewer molecules of gas than the reactants.
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450°C is considered the optimum temperature for the Haber process, why is this?
It is a compromise temperature usually used to give a reasonable yield in a short time. The lower the temperature the greater the yield of ammonia however the reaction rate decreases as the temperature is lowered and it would take longer to produce.
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Why is the yield of ammonia greater at lower temperatures?
Because the forward reaction is exothermic.
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What happens to the iron catalyst when the temperature is lowered?
It becomes ineffective.
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Why do higher pressures increase the costs of an industrial process?
More energy is needed and strong reaction vessels and pipes are needed which both cost more.
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At a temperature of 100°C and 200 atmospheres pressure the yield of ammonia is 98%. Why is the Haber process not done at this temperature?
The reaction would be too slow (rate decreased and catalyst will not work).
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**MAK SURE YOU KNOW THE FACTORS THAT AFFECT THE RATES OF REACTIONS AND UNDERSTAND HOW THEY APPLY TO THE HABER PROCESS**
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Card 2

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Why aren't higher pressures used in the Haber process?

Back

Although higher pressures would produce more ammonia, they would make the chemical plant too expensive to build and run.

Card 3

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What temperature is used in the Haber process and why?

Back

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Card 4

Front

Why is a pressure of about 200 atmospheres used as an optimum pressure for the Haber process?

Back

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Card 5

Front

The higher the pressure the greater the yield of ammonia, why is this?

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