Lesson focus: Extraction method depends on metal reactivity, oreA rock that contains enough metal to make it worth digging up and extracting. chemistry, energy requirements and wider environmental costs.
Select and evaluate extraction methods using the reactivity series, reductionA reaction in which a substance loses oxygen (or gains electrons), such as iron oxide being reduced to iron. and life-cycle evidence.
Build on earlier learning
Metal displacement reactionsDisplacement showed that more reactive metals form ions more readily. The same ordering determines how difficult metal compounds are to reduce.
Practical
Extracting copper with carbon
- Mix copper oxide with carbon powder in a test tube.
- Heat strongly for several minutes.
- Tip the product into water: pink-brown copper sinks.
Record: Observations and the word equation.
Safety: Wear eye protection; let the tube cool before handling.
You will be successful when you can…
- Relate extraction to the reactivity series.
- Explain carbon reduction.
- Explain why electrolysis is needed for reactive metals.
- Evaluate extraction against recycling.
Words that carry the science
- ore
- A naturally occurring material containing enough of a desired mineral for extraction to be worthwhile.
- reduction
- Removal of oxygen or, more generally, gain of electrons.
- smelting
- High-temperature extraction involving heating an ore, often with a reducing agent.
- electrolysis
- Use of electrical energy to decompose an ionic substance.
- carbon footprint
- The total greenhouse-gas emissions associated with a product or activity, expressed as carbon-dioxide equivalent.
- life cycle
- All stages from raw-material extraction through manufacture, use and end-of-life.
Choose extraction routes from chemistry and consequences
01Less reactive metals can be reduced chemically
Metals below carbon in the reactivity series can often be extracted from oxides by heating with carbon or carbon monoxide. The metal oxide is reductionA reaction in which a substance loses oxygen (or gains electrons), such as iron oxide being reduced to iron. because oxygen is removed; carbon species are oxidised.
For example, iron oxide + carbon monoxide → iron + carbon dioxide. Industrial processes involve several reactions, impurities and energy inputs, so this word equation is a useful core model rather than the complete blast-furnace story.
02Very reactive metals need electrolysis
Metals above carbon, such as aluminium, form compounds too stable for carbon reduction under ordinary industrial routes. Molten ionic compounds can be electrolysed so metal ions gain electrons at an electrode.
electrolysisBreaking down an ionic compound, when molten or dissolved in water, using an electric current. can use large amounts of electrical energy. Its carbon footprintThe total amount of greenhouse gases released because of a product or activity. depends strongly on the electricity source as well as mining, processing and transport.
03Recycling changes the life-cycle calculation
Recycling metals commonly uses less energy than extraction from oreA rock that contains enough metal to make it worth digging up and extracting. and reduces mining waste. It also requires collection, sorting, cleaning and remelting, and mixed alloys can be difficult to separate.
A decision should consider ore grade, energy source, emissions, habitat disruption, water use, worker safety, product quality and transport. No single number captures every consequence.
Extracting metals
How a metal is extracted from its ore depends on its reactivity. Metals less reactive than carbon can be extracted by heating the oxide with carbon (reduction). More reactive metals need electrolysis, which uses lots of electricity. The least reactive metals are found as the elements.
Red: extracted by electrolysis. Blue: reduced with carbon. Yellow: found native (some copper is found native too).
Controls
Electrolysis needs a lot of electricity, so it costs more. Recycling metals saves energy and ores.
| Method | Metals | Reason |
|---|---|---|
| Electrolysis | K to Al | Above carbon |
| Carbon | Zn to Cu | Below carbon |
| Native | Ag, Au | Unreactive |
Select an extraction method
Choose a likely route for aluminium and for copper oxide.
- Aluminium is above carbon in the reactivity series.
- Its compound requires electrolysis in the standard model.
- Copper is below carbon.
- Copper oxide can be reduced using carbon under suitable conditions.
How to make the reasoning visible: Reactivity sets a chemical constraint; economics and environmental evidence then shape the industrial choice.
Compare extraction decisions
The figures are illustrative indices per tonne of usable metal, not industrial measurements.
| Route | Relative energy | Main chemical route | Key burden | Potential advantage |
|---|---|---|---|---|
| Iron from ore | Medium | Carbon reduction | CO₂ and mining | Large-scale infrastructure |
| Aluminium from ore | Very high | Electrolysis | Electricity and red-mud waste | High-purity light metal |
| Copper from low-grade ore | High | Concentration then reduction/electrowinning | Waste rock and water | Valuable conductor |
| Recycled aluminium | Low relative to primary | Remelting and refining | Collection and sorting | Large energy saving |
Why can renewable electricity reduce but not eliminate aluminium’s footprint?
Why might recycling not produce metal suitable for every use?
Check your understanding
Answer from memory, then check against the suggested answer.
What is an ore?
Which metals generally need electrolysis?
What does reduction mean for a metal oxide?
A country decarbonises its electricity grid. Which extraction route is affected most directly?
Explain why a low-grade ore can become economically viable without becoming chemically richer.
Exam Question Practice
Exam Question Practice
Mark points shown after marking
A drinks-can manufacturer considers using recycled aluminium instead of new (primary) aluminium extracted by electrolysis.
Give two advantages of recycled aluminium.
(3)Evaluate the plan: give two disadvantages and a conclusion.
(3)Total for this question: 6 marks
Command word: For evaluateA command word: weigh up the good points and bad points, then give your overall judgement., weigh benefits against constraints and finish with a judgement tied to the product specification.