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AQA GCSE · Question 02.1 · Using resources
This question is about ammonia and nitric acid. In the Haber process ammonia is produced from nitrogen and hydrogen. Figure 1 represents the Haber process.
Pipe P links the condenser to the reactor. Why is the condenser linked to the reactor?
This question is about ammonia and nitric acid. In the Haber process ammonia is produced from nitrogen and hydrogen. Figure 1 represents the Haber process.
Pipe P links the condenser to the reactor. Why is the condenser linked to the reactor?
How to approach this question
Look at the diagram. Gases enter the reactor, and liquid ammonia leaves the condenser. The reaction to form ammonia is reversible, meaning not all the reactants are converted to product in one pass. What happens to the reactants that don't react? Pipe P takes something from the condenser back to the reactor. Consider what is still a gas after the ammonia has been condensed into a liquid.
Full Answer
To recycle the unreacted nitrogen and hydrogen gases.
The Haber process (N₂(g) + 3H₂(g) ⇌ 2NH₃(g)) is a reversible reaction that reaches equilibrium. This means that in the mixture leaving the reactor, there is ammonia product as well as unreacted nitrogen and hydrogen. In the condenser, the mixture is cooled. Ammonia has a much higher boiling point (-33 °C) than nitrogen (-196 °C) and hydrogen (-253 °C). Therefore, the ammonia condenses into a liquid and can be removed. The unreacted nitrogen and hydrogen remain as gases. Pipe P recycles these expensive unreacted gases back into the reactor to be passed over the catalyst again. This increases the overall yield and improves the economic efficiency of the process.
Common mistakes
✗ Saying "to cool the reactor".
✗ Saying "to transport ammonia".
✗ Giving a vague answer like "to make it more efficient" without explaining how.
Practice the full AQA GCSE Chemistry Higher Tier Paper 2
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