Figure 6 shows a flow diagram for the Haber process - AQA - GCSE Chemistry - Question 6 - 2016 - Paper 3
Question 6
Figure 6 shows a flow diagram for the Haber process.
Figure 6
Nitrogen gas
Hydrogen gas
Reactor containing iron
Mixture of gases (nitrogen, hydrogen and ammonia)... show full transcript
Worked Solution & Example Answer:Figure 6 shows a flow diagram for the Haber process - AQA - GCSE Chemistry - Question 6 - 2016 - Paper 3
Step 1
Hydrogen gas is obtained from methane. Name one source of methane.
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Answer
One source of methane is natural gas.
Step 2
Air is the source used to produce nitrogen for the Haber process. Suggest why air must not get into the reactor.
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Answer
Air contains oxygen, which can react with and oxidize the hydrogen in the reactor, potentially reducing the efficiency of ammonia production.
Step 3
Describe what happens to the mixture of gases from the reactor.
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The mixture of gases is cooled after passing through the reactor. As a result, ammonia condenses or liquefies, allowing it to be separated from the remaining nitrogen and hydrogen gases. The unreacted nitrogen and hydrogen gases are then recycled and returned to the reactor for further reactions.
Step 4
Use Figure 7 to suggest the conditions that produce the greatest yield of ammonia.
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The conditions that produce the greatest yield of ammonia are at a temperature of 200 °C and a pressure of 1000 atmospheres.
Step 5
Use Figure 7 to suggest and explain why the conditions used to produce ammonia in the Haber process are a temperature of 450 °C and a pressure of 200 atmospheres.
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The reaction in the Haber process is reversible, with the forward reaction being exothermic. A higher temperature generally reduces the yield of ammonia; however, a lower temperature decreases the reaction rate. Thus, 450 °C is a compromise that provides a satisfactory yield and an adequate rate of reaction. Regarding pressure, increasing pressure favors the formation of ammonia due to the reduction in gas volume. However, extremely high pressures involve greater costs and potential risks; therefore, 200 atmospheres is a practical choice that balances yield and economic viability.