What is the Maximum Pressure in kPa for Ammonia in the Haber Process?

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SUMMARY

The maximum pressure for ammonia in the Haber process, when cooled from 450°C to 132.35°C, is calculated using the ideal gas law equation P1/T1 = P2/T2. Given the initial pressure of 76,000 mmHg, the resulting pressure is 5,680 kPa. This calculation assumes that the pressure is solely for ammonia, despite the presence of other gases like H2 and N2. The discussion highlights concerns regarding deviations from ideal gas behavior under the specific conditions of the reaction vessel.

PREREQUISITES
  • Understanding of the Haber process and its operational conditions
  • Familiarity with the ideal gas law and its applications
  • Knowledge of pressure and temperature conversions (mmHg to kPa)
  • Basic principles of gas behavior under varying conditions
NEXT STEPS
  • Study the implications of deviations from ideal gas behavior in chemical processes
  • Learn about pressure-temperature relationships in gas laws
  • Explore the practical applications of the Haber process in industrial settings
  • Investigate methods for measuring and controlling pressure in chemical reactions
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Chemistry students, chemical engineers, and professionals involved in industrial chemistry, particularly those focused on the Haber process and gas behavior under varying conditions.

alingy1
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Hello everyone,
I'm doing some practice problems for my final exam.
I came across this question:

«The Haber process is being used at a pressure of 76 000 mmHg at a temperature of 450°C. Gaseous ammonia is cooled and collected after its production, in order that its temperature does not exceed 132,35°C.
What is the maximum pressure in kPa that ammonia must be into not exceed that temperature? »

So, the answer key of the previous exam I took it from says 5680 kPa. However, I find that a bit weird. It's a basic application of P1/T1=P2/T2... First of all, isn't 76 000mmHg the pressure of all the gases, including H2 and N2? Then, it is said that ammonia is collected, changing the volume of the recipient? What do you think?
 
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Since no one has answered so far: I don't know the answer for sure, but I cannot think of anything else to do with the given data... You have some ammonia at 450 C. You want to cool it to reach 132,35 C. What will be the final pressure? You need to know the initial one which cannot be other that 76000 mmHg because you do not have any data to calculate an use another value...
 
Last edited:
alingy1 said:
Hello everyone,
I'm doing some practice problems for my final exam.
I came across this question:

«The Haber process is being used at a pressure of 76 000 mmHg at a temperature of 450°C. Gaseous ammonia is cooled and collected after its production, in order that its temperature does not exceed 132,35°C.
What is the maximum pressure in kPa that ammonia must be into not exceed that temperature? »

So, the answer key of the previous exam I took it from says 5680 kPa. However, I find that a bit weird. It's a basic application of P1/T1=P2/T2... First of all, isn't 76 000mmHg the pressure of all the gases, including H2 and N2? Then, it is said that ammonia is collected, changing the volume of the recipient? What do you think?

This is a continuous process and I'm assuming that some or all of the ammonia produced at any instant enters a part of the reaction vessel where the pressure is reduced sufficiently. This can result in the cooling necessary to liquify and remove that ammonia.
Application of the ideal equation P1/T1=P2/T2 does give a pressure of 5680kPa as in your answer key so I assume that is all that is needed to answer the question.
It does seem very odd though. The deviations from ideal gas behaviour are enormous within the environmental conditions met in the reaction vessel.
 
Last edited:

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