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The Haber process and the use of NPK fertilisers
This chemistry-only topic links reversible reactions, equilibrium, raw materials and industrial process design to fertiliser manufacture.
30
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150
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150
Questions
90 min
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30 objective pages available
The Haber process15 objectives
- Describe the Haber process as the industrial manufacture of ammonia. (Chemistry only)
- Explain that ammonia can be used to make nitrogen-based fertilisers. (Chemistry only)
- Recall nitrogen and hydrogen as the raw materials for the Haber process. (Chemistry only)
- Recall air as a source of nitrogen for the Haber process. (Chemistry only)
- Recall methane or natural gas and steam as a source of hydrogen for the Haber process. (Chemistry only)
- Describe purified nitrogen and hydrogen passing over an iron catalyst. (Chemistry only)
- Recall typical Haber process conditions of about 450 degrees Celsius and about 200 atmospheres. (Chemistry only)
- Describe ammonia formation as a reversible reaction. (Chemistry only)
- Explain why cooling allows ammonia to liquefy and be removed from the reaction mixture. (Chemistry only)
- Explain why unreacted nitrogen and hydrogen are recycled. (Chemistry only)
- Interpret graphs of reaction conditions versus rate. (HT only; Chemistry only; MS 1a, 1c)
- Apply dynamic equilibrium ideas to the Haber process. (HT only; Chemistry only)
- Explain the trade-off between rate of production and equilibrium yield in the Haber process. (HT only; Chemistry only)
- Explain how industrial conditions are chosen by considering raw material availability, energy costs, equilibrium position and rate. (HT only; Chemistry only; WS 3.5, 3.8)
- Distinguish rate considerations from equilibrium yield considerations in the Haber process. (HT only; Chemistry only)
Production and uses of NPK fertilisers15 objectives
- Explain that nitrogen, phosphorus and potassium compounds are used in fertilisers to improve agricultural productivity. (Chemistry only)
- Define NPK fertilisers as fertilisers containing compounds of nitrogen, phosphorus and potassium. (Chemistry only)
- Describe NPK fertilisers as formulations of salts containing appropriate percentages of elements. (Chemistry only)
- Explain that industrial production of NPK fertilisers can use several raw materials and integrated processes. (Chemistry only)
- Explain that ammonia can be used to manufacture ammonium salts. (Chemistry only)
- Explain that ammonia can be used to manufacture nitric acid. (Chemistry only)
- Recall that potassium chloride and potassium sulfate are obtained by mining. (Chemistry only)
- Recall that phosphate rock is obtained by mining but cannot be used directly as a fertiliser. (Chemistry only)
- Describe treatment of phosphate rock with nitric acid to produce soluble salts for fertilisers. (Chemistry only)
- Describe treatment of phosphate rock with sulfuric acid to produce soluble salts for fertilisers. (Chemistry only)
- Describe treatment of phosphate rock with phosphoric acid to produce soluble salts for fertilisers. (Chemistry only)
- Recall the names of salts made when phosphate rock reacts with nitric acid, sulfuric acid and phosphoric acid. (Chemistry only)
- Compare industrial fertiliser production with laboratory preparation of similar compounds using given information. (Chemistry only)
- Prepare an ammonium salt. (Chemistry only; AT 4)
- Distinguish NPK fertiliser manufacture from the Haber process that produces ammonia.
Key terms
Haber processammonianitrogen-based fertilisersraw materialsnitrogen sourcehydrogen sourceiron catalystHaber process conditionsammonia productionreversible reactionliquefyrecycling of reactants
Exam tips
- Understand the Haber Process: Remember to familiarize yourself with the steps of the Haber process, including the reactants, conditions, and the role of the iron catalyst. Link your answer to The Haber process in The Haber process and the use of NPK fertilisers, and keep the biology specific to chemistry only.
- Understand Ammonia's Role: Remember to focus on how ammonia is utilized in the production of nitrogen-based fertilizers, including its benefits for agricultural productivity. Link your answer to The Haber process in The Haber process and the use of NPK fertilisers, and keep the biology specific to chemistry only.
Common mistakes
- Misunderstanding the Haber Process: Remember that the Haber process specifically uses nitrogen and hydrogen as raw materials to produce ammonia.
- Misunderstanding Ammonia's Role: Ammonia is a raw material used to produce nitrogen-based fertilisers, but they are not the same substance.
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