AQA · Chemistry · 8462

GCSE Chemistry (AQA): The Haber Process

Topic 10 — Using Resources. Generated from the caption track of Cognito's lesson video "GCSE Chemistry - The Haber Process Explained (2026/27 exams)"; each card deep-links to the moment in the video it came from. Lesson 10.12 of Cognito's AQA GCSE Chemistry (Triple) course (Higher tier), filed under AQA Chemistry 8462. Teaching by Cognito — https://cognitoedu.org/coursesubtopic/c2-gcse-aqa-h-t_10.12.

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  1. Why does high pressure increase the equilibrium yield of ammonia?

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    There are fewer gas molecules on the product side, so high pressure shifts the equilibrium to the right.

  2. Which catalyst is used in the Haber process?

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    Iron.

  3. What limits how high the pressure in the Haber process can be made?

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    Practical considerations — high pressures are very expensive to maintain and dangerous.

  4. What pressure is used in the Haber process?

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    200 atmospheres.

  5. Where is the hydrogen for the Haber process obtained from?

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    From hydrocarbons such as methane (natural gas).

  6. What temperature is used in the Haber process?

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    450 °C — a compromise between a good rate and an acceptable yield.

  7. What is ammonia from the Haber process mainly used to make?

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    Nitrogen-based fertilisers, which allow us to grow enough food.

  8. Which two gases are the reactants in the Haber process?

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    Nitrogen and hydrogen.

  9. How is ammonia separated from unreacted nitrogen and hydrogen?

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    The mixture is cooled in a condenser; ammonia has a higher boiling point than N₂ and H₂, so it condenses to a liquid while they stay gaseous.

  10. Why would a lower temperature increase the yield of ammonia?

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    The forward reaction is exothermic, so a lower temperature shifts the equilibrium towards the products.

  11. The forward reaction of the Haber process is ?, and the reaction is reversible.

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    exothermic

  12. Where is the nitrogen for the Haber process obtained from?

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    From the air, which is 78% nitrogen.

  13. Why is 450 °C used rather than a lower temperature in the Haber process?

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    It is a compromise: the yield is lower, but the rate of reaction is much higher (and heating costs are kept down).

  14. What happens to the unreacted nitrogen and hydrogen after the condenser?

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    They are recycled back into the reaction vessel.

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