Using Resources
What's covered
Key facts
Aluminium does not corrode away even though it is reactive because a thin oxide layer (Al₂O₃) forms on its surface and prevents further oxidation.
Ammonium nitrate (NH₄NO₃) is a common nitrogen-rich fertiliser, made by reacting ammonia with nitric acid.
Crude oil is a finite resource.
A life cycle assessment (LCA) evaluates the environmental impact of a product from raw-material extraction to disposal.
Aluminium is extracted by electrolysis rather than carbon reduction because aluminium is more reactive than carbon, so carbon cannot reduce its oxide.
Ammonia from the Haber process is mainly used to make nitrogen fertilisers.
Chlorine is added to drinking water to kill microorganisms.
Painting and oiling iron prevent rusting by acting as physical barriers that keep water and oxygen away from the metal.
Industrial route: NH₃ is oxidised (Ostwald process) to HNO₃; then NH₃ + HNO₃ → NH₄NO₃.
Crude oil is classed as a finite resource because it forms over millions of years, far slower than we extract it.
Sample questions
A taste of the 70 questions in this topic — answers marked. Sign up to practise the full set with spaced repetition.
What two substances are needed for iron to rust?
- •Oxygen and dissolved salt (both required for rusting to occur)
- •Water and carbon dioxide (both must be present together)
- ✓Water and oxygen (both are required simultaneously)
- •Water only — oxygen in the air is not required for iron to rust
Which three elements do NPK fertilisers provide?
- •Carbon, hydrogen, oxygen
- •Nitrogen, oxygen, calcium
- ✓Nitrogen, phosphorus, potassium
- •Sodium, potassium, sulfur
What is the difference between a finite and a renewable resource?
- •Finite resources are made in factories; renewables occur only in nature
- •Finite resources are solids from the ground; renewables are gases or liquids
- ✓Finite resources are used faster than they form; renewable resources replenish naturally
- •Finite resources give more energy; renewables last longer but give less
What are the four stages considered in a Life Cycle Assessment (LCA) of a product?
- •Importing by ship; warehouse storage; retail; consumer use at home
- •Mining of ores; smelting; forming by rolling; painting for protection
- ✓Raw material extraction; manufacturing/packaging; product use; disposal
- •Research and design; safety testing; sales and marketing; customer feedback
How is iron extracted in a blast furnace?
- ✓Carbon (coke) reduces iron oxide at high temperature, releasing molten iron
- •Iron ore is electrolysed at high temperature: Fe at cathode, O₂ at anode
- •Iron ore is heated with H₂, which removes the oxygen and leaves pure iron
- •Iron oxide reacts with steam at high pressure to release iron
What are the raw materials for the Haber process?
- •Carbon from coal and nitrogen from ammonia
- ✓Nitrogen (from the air) and hydrogen (from natural gas)
- •Nitrogen from ammonia and hydrogen from electrolysis of water
- •Oxygen from the air and hydrogen from water
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