Making ammonia, why the conditions are a compromise, recycling unreacted gases, NPK fertilisers and the percentage of a nutrient in a fertiliser.
What you will learn
- State the Haber process conditions and raw materials
- Explain the compromise between yield, rate and cost (Higher)
- Read yield data and calculate reacting masses of ammonia
- Calculate the percentage of nitrogen by mass in a fertiliser
Making ammonia
nitrogen + hydrogen ⇌ ammonia
N₂ + 3H₂ ⇌ 2NH₃ (forward reaction exothermic)
- Raw materials: nitrogen from the air; hydrogen usually from natural gas.
- The purified gases pass over an iron catalyst at about 450 °C and 200 atmospheres.
- The reaction is reversible, so only some of the gases react. On cooling, ammonia liquefies and is removed; the unreacted nitrogen and hydrogen are recycled.
The rest of this lesson and its 10 practice questions are locked.
In this lesson
- Making ammonia
- Why these conditions (Higher)
- NPK fertilisers
- Try it: Check an Mr with the calculator
10 practice questions, marked as you go; about 25 minutes in all.
Key terms
Iron catalyst, Liquefies
In this unit: The Earth's atmosphere
The air now and how it formed, greenhouse gases and climate change, carbon footprints and the pollutants from burning fuels. Its later lessons on water, life cycles, materials and the Haber process stay here too; Using resources teaches them in full.