What are the common methods used for the extraction of metals in Edexcel IGCSE Chemistry?

In Edexcel IGCSE Chemistry, the common methods for extracting metals include electrolysis and reduction with carbon. Electrolysis is used for metals that are more reactive than carbon, such as aluminum, while reduction with carbon is used for less reactive metals like iron. These methods are essential for obtaining pure metals from their ores.

Why is electrolysis used for extracting certain metals in Inorganic Chemistry?

Electrolysis is used for extracting metals that are highly reactive and cannot be reduced by carbon. In the Edexcel IGCSE curriculum, this process is particularly important for metals like aluminum. During electrolysis, an electric current is passed through a molten ore, causing the metal ions to gain electrons and form pure metal.

How does the reactivity series influence the method of metal extraction?

The reactivity series is a list of metals arranged in order of decreasing reactivity. In Edexcel IGCSE Chemistry, it helps determine the method of extraction. Highly reactive metals, such as potassium and sodium, are extracted using electrolysis, while less reactive metals like iron can be extracted by reduction with carbon. This series is crucial for predicting how metals will react with other substances.

What are some common uses of metals studied in Edexcel IGCSE Chemistry?

Metals have a wide range of uses due to their properties. For instance, aluminum is used in aircraft manufacturing because of its low density and resistance to corrosion. Iron is used in construction and manufacturing due to its strength and abundance. Copper is used in electrical wiring because of its excellent conductivity. These applications are covered in the Edexcel IGCSE Chemistry syllabus.

Why is recycling metals important in the context of Edexcel IGCSE Chemistry?

Recycling metals is crucial because it conserves natural resources, reduces energy consumption, and minimizes environmental impact. In Edexcel IGCSE Chemistry, students learn that recycling metals like aluminum saves up to 95% of the energy required to extract it from its ore. This process also reduces the need for mining, which can be harmful to the environment.

Why is "Writing 'C reduces Fe₂O₃' as the main blast furnace reduction step" a common mistake in Extraction and Uses of Metals?

Why it happens: Knowing that the furnace 'uses carbon to reduce iron ore'. How to avoid it: The ACTUAL reducing agent is CO, not C. The reaction sequence is: (1) C + O₂ → CO₂ (combustion); (2) CO₂ + C → 2CO (CO formation); (3) Fe₂O₃ + 3CO → 2Fe + 3CO₂ (MAIN reduction). Write all three to get full marks. Source: 4CH1 Examiner Reports 2022-2024

Why is "Stating that cryolite REACTS with Al₂O₃ to form aluminium" a common mistake in Extraction and Uses of Metals?

Why it happens: Confusing solvent with reactant. How to avoid it: Cryolite is a SOLVENT — it dissolves Al₂O₃ to lower the operating temperature. It is NOT a reactant; it is RECOVERED unchanged after the electrolysis. The ions discharged at the electrodes are Al³⁺ and O²⁻ from Al₂O₃, not from cryolite. Source: 4CH1 Examiner Reports 2023-2024

Why is "Writing the half-equations backwards in aluminium electrolysis" a common mistake in Extraction and Uses of Metals?

Why it happens: Confusing which electrode is which. How to avoid it: Cathode (NEGATIVE) attracts CATIONS (positive) — Al³⁺ → Al. Anode (POSITIVE) attracts ANIONS (negative) — O²⁻ → O₂. Memorise: 'PANIC — Positive Anode Negative Is Cathode'.

Why is "Calling slag a 'waste product' of the blast furnace" a common mistake in Extraction and Uses of Metals?

Why it happens: Confusing it with the actual waste gases. How to avoid it: Slag is NOT waste — it is sold for road-building (aggregate), breeze blocks and fertiliser ingredients. The actual 'waste' is the gases (CO₂, CO, N₂) that exit the top; these are scrubbed and partly reused.

Why is "Saying that gold is extracted from a 'gold ore' chemically" a common mistake in Extraction and Uses of Metals?

Why it happens: Generalising the metal extraction theme. How to avoid it: Gold occurs NATIVE — uncombined in nature, as nuggets and flakes. No chemical extraction is needed. Methods are PHYSICAL: panning, crushing, cyanide leaching (which is technically chemical, but produces dissolved Au⁺ that's then precipitated, not from an oxide). Source: 4CH1 Examiner Reports 2022-2024

Why is "Stating that recycling aluminium 'saves 50%' or 'saves 5%' of the energy" a common mistake in Extraction and Uses of Metals?

Why it happens: Confusing 'uses 5%' (recycling) with 'saves 50%' (a different statistic). How to avoid it: Recycling Al USES ~5% of the energy of primary extraction → SAVES ~95% of the energy. Many candidates flip these. Memorise: '95% energy saving from recycling Al'.

Inorganic ChemistryPearson Edexcel IGCSE Chemistry 4CH1 Higher

Extraction and Uses of Metals

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next.

Previous Next

Learn this Topic

Start with the slides for the quick version, then go deeper with the full study notes.

Short Study Notes in the form of Slides

Read the notes first. If the method in a worked example clicks, you're ready for the questions.

Short Study Notes — Extraction and Uses of Metals

Start with these resources to cover the key concepts, then work through the practice questions.

Page 1 / 0

Detailed Notes

Full prose, callouts and a recap — built for A* mastery, not just a quick scan.

Take these study notes with you

Download a branded PDF — full prose, callouts, recap and memorise list for Extraction and Uses of Metals, ready to print or save offline.

Extraction and Uses of Metals — Pearson Edexcel International GCSE Chemistry 4CH1 Study Notes (2026 onwards, Spec Issue 4)

Method of extracting a metal depends on its position in the reactivity series. Metals MORE reactive than carbon (K, Na, Ca, Mg, Al) require ELECTROLYSIS of the molten ore. Metals LESS reactive than carbon (Zn, Fe, Cu, etc.) are extracted by REDUCTION with carbon (much cheaper). Unreactive metals (Au, Ag, Pt) occur native. Detailed cases: aluminium (electrolysis of Al₂O₃ in cryolite; carbon anode burns as CO₂) and iron (blast furnace with coke + Fe₂O₃ + limestone; CO reduces Fe₂O₃; slag removes silica). Common uses of metals and alloys; environmental + economic case for recycling.

At a glance

Metals ABOVE C in series (K, Na, Ca, Mg, Al) → extracted by ELECTROLYSIS of molten ore.
Metals BELOW C (Zn, Fe, Cu, Sn, Pb) → extracted by REDUCTION with carbon (cheaper).
Unreactive metals (Au, Ag, Pt) → found NATIVE; physical separation only.
Aluminium: Al₂O₃ in molten cryolite (lowers mp 2050 → 950 °C); cathode Al; anode O₂; C anode + O₂ → CO₂.
Iron blast furnace: coke + Fe₂O₃ + limestone + hot air. Main reduction: Fe₂O₃ + 3CO → 2Fe + 3CO₂.
Limestone forms slag: CaCO₃ → CaO; CaO + SiO₂ → CaSiO₃ (floats on Fe; removes silica).
Uses: Al (low density - aircraft, cans); Cu (conductivity - wiring); steel (strength - construction, cars); brass/bronze (decorative + strong).
Recycling: Al saves ~95% energy; Cu ~80%; conserves ores; less mining and landfill.

What you’ll learn

Mapped to the Cambridge IGCSE 4CH1 syllabus (2026 onwards).

2.22 — Understand that the method used to extract a metal from its ore is related to its position in the reactivity series.
2.23 — Describe the extraction of metals less reactive than carbon (e.g. iron, zinc) by reduction with carbon or carbon monoxide.
2.24 — Describe the use of electrolysis to extract metals more reactive than carbon (e.g. aluminium, sodium).
2.26 — Describe the extraction of aluminium from purified Al₂O₃ by electrolysis, including the role of cryolite, the cathode and anode half-equations, and why the carbon anode wears away.
2.27 — Recall the half-equations for aluminium extraction: cathode Al³⁺ + 3e⁻ → Al; anode 2O²⁻ → O₂ + 4e⁻.
2.28 — Describe the extraction of iron from haematite (Fe₂O₃) in the blast furnace, including the raw materials (iron ore, coke, limestone, hot air).
2.29 — Write equations for the reactions in the blast furnace: C + O₂ → CO₂; CO₂ + C → 2CO; Fe₂O₃ + 3CO → 2Fe + 3CO₂; CaCO₃ → CaO + CO₂; CaO + SiO₂ → CaSiO₃ (slag).
2.32 — Describe the uses of common metals: aluminium (aircraft, cans, cables); copper (wiring, plumbing); iron/steel (construction, cars); and common alloys (brass, bronze, stainless steel).
2.33 — Explain the environmental and economic advantages and disadvantages of recycling metals.
2.34 — Describe a life-cycle assessment (LCA) comparing the environmental impact of products over their full life cycle.
2.35 — Understand the importance of conserving finite ore resources and the role of recycling in this.

Why method depends on reactivity (spec 2.22, 2.23, 2.24)

Above C → electrolysis. Below C → carbon reduction. Below H + unreactive → native.

The big idea. The method used to extract a metal from its ore depends on how strongly the metal holds onto its oxide / sulfide / halide. More reactive metals hold their compounds tightly; less reactive metals release them readily. Carbon is the natural reference: if C can take the oxygen FROM the metal oxide, carbon reduction is sufficient. If not, more energetic electrolysis is needed.

The three categories.

Position in reactivity series	Examples	Method
ABOVE carbon	K, Na, Ca, Mg, Al	ELECTROLYSIS of molten ore
BELOW carbon (and above H)	Zn, Fe, Sn, Pb	Reduction with C / CO
BELOW hydrogen (very unreactive)	Au, Ag, Pt, (Cu)	Found NATIVE; physical separation

Extraction method depends on the metal's position relative to carbon in the reactivity series.

1. Electrolysis — for K, Na, Ca, Mg, Al.

Carbon CANNOT reduce these oxides because the metal is more reactive than carbon — i.e. the metal holds the oxygen more strongly than carbon does. We must use an even more powerful reducing process: ELECTROLYSIS forces electrons onto the metal cation using electrical energy.

Examples:

Sodium: electrolysis of MOLTEN NaCl in the Downs cell.
Magnesium: electrolysis of molten MgCl₂.
Aluminium: electrolysis of Al₂O₃ dissolved in cryolite.

Electrolysis is EXPENSIVE because it consumes huge amounts of electrical energy. Used only when necessary.

2. Carbon reduction — for Zn, Fe, Sn, Pb, (Cu).

When the metal is LESS reactive than carbon, carbon CAN take the oxygen and form CO₂ (or CO), reducing the metal oxide. This is done at high temperature in a furnace.

Examples:

Iron: Fe₂O₃ + 3CO → 2Fe + 3CO₂ in a blast furnace.
Zinc: ZnO + C → Zn + CO at high temperature.
Copper (low-grade ore): Cu₂O + C → 2Cu + CO.

Carbon reduction is MUCH CHEAPER than electrolysis — it only needs heat, not electricity. So we use it whenever the metal allows.

3. Native (found uncombined) — for Au, Ag, Pt, sometimes Cu.

Some metals are so unreactive that they exist in nature as the FREE ELEMENT. Gold is the classic example — found as nuggets or fine flakes in alluvial deposits and quartz veins. No chemical extraction is needed; just physical separation:

Panning: dense gold sinks in water-washed gravel.
Crushing + cyanide leaching: dissolves gold from finely-crushed ore as a complex; precipitated and refined.
Electrorefining: final purification by electrolysis.

Silver and platinum also occur native and are extracted by similar physical methods.

Why not electrolysis for everything? Electrolysis WOULD work for iron, copper etc., but it's MUCH more expensive than the alternative. With ~1.5 billion tonnes of steel produced worldwide each year, the cost difference is enormous. Use the cheapest method that works.

Choosing the method — algorithm.

Look up the metal in the reactivity series.
Above C? Use electrolysis.
Below C but above H? Use C/CO reduction.
Below H and very unreactive? Look for native deposits.

Above C → ELECTROLYSIS (expensive but only way).
Below C → carbon reduction (much cheaper).
Below H + very unreactive → found native, physical separation.
Use cheapest method that works for the metal in question.

See the full worked example for extraction and uses of metals →

Aluminium extraction by electrolysis (spec 2.26, 2.27)

Al₂O₃ dissolved in molten cryolite at ~950 °C; cathode Al; anode O₂; C anode burns as CO₂.

The challenge. Aluminium is the third-most-abundant element in Earth's crust (~8% by mass), but it took until 1886 for an economic extraction process (the Hall–Héroult process) to be developed. Why so hard? Because aluminium is ABOVE carbon in the reactivity series, so carbon reduction doesn't work — and pure Al₂O₃ melts at the eye-watering temperature of ~2050 °C.

The breakthrough — using cryolite as a solvent. Cryolite (Na₃AlF₆) is a mineral that DISSOLVES Al₂O₃ at a much lower temperature. The mixture's mp is ~950 °C — energy-affordable.

The Hall–Héroult cell — apparatus.

Large steel tank lined with carbon (graphite) — this lining is the CATHODE (negative electrode).
Several carbon blocks dipped from above into the molten mix — these are the ANODES (positive electrodes).
The molten mixture: Al₂O₃ dissolved in cryolite at ~950 °C.
A very large DC current (~100,000-300,000 A) is passed through the cell.

Process. Al₂O₃ in the melt ionises (essentially):

$\text{Al}_2\text{O}_3 \rightarrow 2\text{Al}^{3+} + 3\text{O}^{2-}$

The ions migrate to the electrodes and are discharged.

Cathode (reduction):

$\text{Al}^{3+}\text{(l)} + 3e^- \rightarrow \text{Al(l)}$

Molten aluminium forms at the cathode. Because Al (mp 660 °C) is liquid at 950 °C, and is DENSER than the cryolite mixture, it pools at the bottom of the cell. It is tapped off periodically and cast into ingots.

Anode (oxidation):

$2\text{O}^{2-}\text{(l)} \rightarrow \text{O}_2\text{(g)} + 4e^-$

Oxygen gas is evolved at the carbon anode. (Note the stoichiometry — each O²⁻ has charge 2−, so two O²⁻ ions release 4 electrons to form one O₂ molecule.)

Why the carbon anode wears away.

The anode operates at ~950 °C and is in direct contact with hot O₂. Hot carbon reacts with oxygen:

$\text{C(s)} + \text{O}_2\text{(g)} \rightarrow \text{CO}_2\text{(g)}$

Some CO is also formed. The carbon anode is gradually 'eaten away' as CO₂. The anodes get thinner over weeks of operation and must be REPLACED REGULARLY — a significant running cost.

Energy and cost. Aluminium production is extremely energy-intensive: ~14 MWh per tonne of Al produced. Worldwide aluminium electrolysis consumes ~3.5% of global electricity. For this reason, smelters are often located near cheap hydroelectric or geothermal power (Iceland, Norway, Canada).

Why we still use aluminium despite the cost. Aluminium has a unique combination of properties:

Low density (~2.70 g/cm³) — about 1/3 that of steel. Critical for aircraft, cars, drink cans.
Strong (especially in alloys like duralumin).
Excellent corrosion resistance — forms a thin tough Al₂O₃ layer that protects from further oxidation.
Good electrical conductor — used for long-distance power transmission lines (lighter than copper).
Good thermal conductor and reflector — used for cooking foil and insulation.
Non-toxic — used for food packaging.
Easily recycled — 95% energy saving versus primary production.

Al₂O₃ dissolved in molten cryolite at ~950 °C (vs ~2050 °C pure).
Cryolite lowers mp → saves energy; not a reactant.
Cathode: Al³⁺ + 3e⁻ → Al (molten Al taps from bottom).
Anode: 2O²⁻ → O₂ + 4e⁻ (oxygen evolved).
Hot C anode reacts with O₂: C + O₂ → CO₂ → anode wears away → replace regularly.
Energy-intensive — hence recycling is so important (95% saving).

See the full worked example for extraction and uses of metals →

Iron extraction in the blast furnace (spec 2.28, 2.29)

Coke + Fe₂O₃ + limestone + hot air. Main reduction: Fe₂O₃ + 3CO → 2Fe + 3CO₂.

The setup. A blast furnace is a tall (40+ m) tower lined with refractory bricks. It is continuously charged from the top with three solid raw materials and has hot air blown in near the bottom.

Raw materials.

Iron ore — usually haematite (Fe₂O₃) or magnetite (Fe₃O₄).
Coke — refined coal, mostly C. Provides both heat (combustion) and the reducing agent (via CO).
Limestone — CaCO₃. Removes the acidic silica (SiO₂) impurity from the ore.

Hot air (~1200 °C) is blasted in near the bottom of the furnace.

Carbon monoxide reduces the iron ore; limestone removes silica as slag that floats on the iron.

The four key reactions.

Reaction 1 — Combustion of coke (heat source).

$\text{C(s)} + \text{O}_2\text{(g)} \rightarrow \text{CO}_2\text{(g)}$

Highly exothermic. The temperature near the bottom reaches ~2000 °C.

Reaction 2 — CO₂ reduced to CO (creates the reducing agent).

$\text{CO}_2\text{(g)} + \text{C(s)} \rightarrow 2\text{CO(g)}$

The CO₂ rises through more hot coke and is partially reduced to carbon monoxide. CO is the ACTUAL REDUCING AGENT for the iron ore.

Reaction 3 — Main extraction: CO reduces Fe₂O₃.

$\text{Fe}_2\text{O}_3\text{(s)} + 3\text{CO(g)} \rightarrow 2\text{Fe(l)} + 3\text{CO}_2\text{(g)}$

The KEY reaction. Carbon monoxide reduces the iron oxide to molten iron, which drains to the bottom of the furnace. This happens in the middle of the furnace at ~1000-1500 °C.

Reaction 4 — Thermal decomposition of limestone.

$\text{CaCO}_3\text{(s)} \rightarrow \text{CaO(s)} + \text{CO}_2\text{(g)}$

At the cooler upper levels of the furnace, limestone breaks down. The CaO produced is needed for the next step.

Slag formation — removing silica impurities.

Iron ore contains silica (sand, SiO₂) as an ACIDIC impurity. CaO is a BASE, so it reacts:

$\text{CaO(s)} + \text{SiO}_2\text{(s)} \rightarrow \text{CaSiO}_3\text{(l)}$

The product, calcium silicate (CaSiO₃) — known as SLAG — is a molten liquid LESS DENSE than molten iron. It floats on top of the iron at the bottom of the furnace and is tapped off SEPARATELY.

Slag is NOT waste. It is sold for road-building (aggregate), fertiliser ingredients (calcium and silica) and breeze blocks for construction.

Products of the furnace.

Molten iron ('pig iron'), tapped from the bottom. Contains ~4% C and other impurities. Sent for further refining (basic oxygen process) to make steel.
Slag (CaSiO₃), tapped separately.
Waste gases (CO₂, CO, N₂) exit the top. Cleaned and partially recycled to preheat the incoming hot air ('regenerative heating') — improves efficiency.

Why continuous operation?

The furnace takes DAYS to heat up to operating temperature — restarting after a shutdown costs enormous energy.
Cooling and reheating stresses the refractory brick lining → cracks → expensive repairs.
Production economics — a typical blast furnace produces ~10,000 tonnes of iron PER DAY.

So blast furnaces run 24/7/365 for years between major rebuilds (typically 15-20 year 'campaigns').

From pig iron to steel. Pig iron is brittle because of its high carbon content (~4%). To make steel, the carbon content is reduced to 0.05-2% by blowing O₂ through molten pig iron in a Basic Oxygen Furnace. Some carbon and other impurities oxidise and are removed. Steel is harder, stronger, and tougher than pure iron or pig iron.

Raw materials: Fe₂O₃ (haematite), coke (C), CaCO₃ (limestone), hot air.
C + O₂ → CO₂ (combustion, heat).
CO₂ + C → 2CO (forms reducing agent).
Fe₂O₃ + 3CO → 2Fe + 3CO₂ (MAIN reduction).
CaCO₃ → CaO + CO₂; CaO + SiO₂ → CaSiO₃ (slag floats; removes silica).
Continuous operation — heating up costs huge energy.

See the full worked example for extraction and uses of metals →

Uses of common metals and alloys (spec 2.32)

Each metal/alloy chosen for specific properties: density, conductivity, strength, corrosion resistance.

Choosing the right metal for a job is about matching the properties to the application. Below are the most common cases tested in 4CH1.

Aluminium — used for aircraft, cans, foil, power cables.

Properties: LOW density (1/3 of steel), STRONG (in alloys), CORROSION-RESISTANT (Al₂O₃ layer), GOOD conductor (heat + electricity), NON-TOXIC, RECYCLABLE.

Applications:

Aircraft bodies + frames — low density essential for fuel efficiency; alloys (duralumin = Al + Cu + Mg + Mn) make it as strong as steel.
Drink cans + food packaging — light, non-toxic, easily recycled, doesn't react with most foods/drinks (oxide layer protects).
Power cables (especially long-distance) — lighter than copper, so cables can sag less between pylons. Slightly lower conductivity than copper, but compensated by larger cross-section.
Cooking foil and pans — good thermal conductor; light.
Window frames + cladding — corrosion-resistant outdoors.

Copper — used for electrical wiring, plumbing, electronics.

Properties: EXCELLENT electrical conductor (2nd to silver, but cheaper), DUCTILE (drawn into wires), MALLEABLE (bent and shaped), CORROSION-RESISTANT (in water), ANTIMICROBIAL, easily JOINED by soldering.

Applications:

Electrical wiring — power cables, household wiring, electronics. ≥99.99% pure copper (electrolytically refined) for lowest resistance.
Plumbing pipes — corrosion-resistant in water, soldered easily, malleable for bending.
Heat exchangers — good thermal conductor.
Roofs — develops green patina (basic copper carbonate) which is itself corrosion-resistant; lasts centuries (cathedrals, statues).

Iron and steel — used for construction, cars, ships, tools.

Properties: STRONG, CHEAP, easily SHAPED (rolled, pressed, forged), MAGNETIC, RECYCLABLE.

Mild steel (Fe + 0.1-0.3% C):

Construction: bridges, beams, reinforced concrete.
Cars: body panels, chassis.
Ships: hulls.
Tools: hammers, wrenches.

Limitation: rusts. Must be painted or galvanised.

Stainless steel (Fe + ~18% Cr + ~8% Ni):

Cutlery — corrosion-resistant.
Surgical instruments — non-corroding, sterilisable, biocompatible.
Kitchen sinks, food-processing equipment.
Architectural cladding (e.g. the Gateway Arch in St Louis).

The Cr forms a thin Cr₂O₃ layer that prevents corrosion of the iron beneath — even when scratched.

Common alloys.

Alloy	Composition	Key properties	Uses
Steel	Fe + 0.1-2% C	Strong, cheap	Construction, cars
Stainless steel	Fe + Cr + Ni	Corrosion-resistant	Cutlery, surgery
Brass	Cu (~70%) + Zn (~30%)	Hard, decorative, antimicrobial	Door handles, instruments
Bronze	Cu + Sn	Hard, corrosion-resistant	Statues, bells, propellers
Duralumin	Al + Cu + Mg + Mn	Strong + low density	Aircraft
Solder	Sn + Pb (older) or Sn + Cu + Ag (lead-free)	Low mp	Joining metal parts

Why alloys are stronger than pure metals. In a pure metal, atoms are all the same size and arranged in regular layers that slide past each other under stress (making the metal soft). In an alloy, atoms of DIFFERENT SIZES disrupt the regular lattice → layers cannot slide as easily → harder and stronger.

This is why pure copper is too soft for door handles (brass is preferred) and pure iron is too soft for construction (steel — Fe + C — is much stronger).

Aluminium: low density + corrosion-resistant → aircraft, cans, cables.
Copper: high conductivity + ductile → wiring, plumbing.
Mild steel (Fe + C): strong + cheap → construction, cars.
Stainless steel (Fe + Cr + Ni): corrosion-resistant → surgery, cutlery.
Alloys (brass, bronze) harder than pure metals — atoms of different sizes disrupt lattice.

See the full worked example for extraction and uses of metals →

Recycling and life-cycle assessment (spec 2.33, 2.34, 2.35)

Recycling saves energy + conserves ores + reduces mining/waste. Aluminium ~95% saving; copper ~80%.

Why recycle metals?

Most metal ores are FINITE resources — there is only so much in Earth's crust, and economic-grade ores are limited. Mining causes environmental damage (deforestation, habitat loss, water pollution, dust). Smelting and electrolysis consume enormous energy. Metal objects don't biodegrade and accumulate in landfill.

Recycling addresses all of these problems by recovering metals from used products and reprocessing them into new ones.

Key advantages of recycling.

Massive energy savings.

Metal Energy saving (vs primary)
Aluminium ~95%
Copper ~80%
Steel ~60-70%
Lead ~65%

For aluminium, recycling melts existing metal (~660 °C) instead of running the energy-intensive electrolysis. The 95% saving is one of the highest of any material.
Reduces fossil-fuel use + CO₂ emissions. Lower energy use → less coal/gas burned in power stations → lower greenhouse-gas emissions.
Conserves finite ore reserves. Bauxite, copper ores, iron ores are not infinite. Recycling stretches their lifespan.
Less mining. Less land disturbance, less deforestation, less water pollution from acidic mine drainage.
Less waste / landfill. Metals can be recycled indefinitely without losing quality. Aluminium and steel can be melted down and reused many times.
Economic benefits. Often cheaper than primary extraction (especially for aluminium and copper); creates recycling industry jobs.

Metal	Energy saving (vs primary)
Aluminium	~95%
Copper	~80%
Steel	~60-70%
Lead	~65%

Disadvantages and limitations.

Cost of collection + sorting. Kerbside collection, transport, automated sorting facilities all cost money and energy.
Contamination. Mixed scrap, paint, food residues, plastic labels need to be separated.
Some items too small/light to be economic. Aluminium foil is light, contaminated, expensive to sort → less commonly recycled than cans.
Some alloys hard to separate. Stainless steel can be recovered, but separating Cr and Ni from Fe is difficult.
Quality control. Some applications (electronics) demand very pure metal; recycled may not always meet specifications.

Practical strategies to increase recycling.

Kerbside recycling programmes — separate bins for cans, plastics, paper.
Deposit-return schemes — pay-back on cans/bottles (Germany, Sweden, some US states).
Producer responsibility — manufacturers must take back their products at end-of-life (EU WEEE Directive for electronics).
Design for recycling — products designed to be easily disassembled and materials separated.
Public education + labelling — clear instructions on what can/can't be recycled.

Life-cycle assessment (LCA).

An LCA is a systematic comparison of the ENVIRONMENTAL IMPACT of a product over its FULL LIFE CYCLE — from raw materials to disposal. Key stages:

Raw material extraction. Mining ore, processing.
Manufacture. Smelting, refining, alloying, forming the product.
Distribution. Transport, packaging.
Use phase. Energy used during operation; emissions; wear.
End of life. Disposal — recycling, incineration, or landfill.

For each stage, the LCA quantifies: energy used, CO₂ emitted, water used, waste produced, other environmental harms.

Example — aluminium can vs glass bottle for soft drinks.

Stage	Aluminium can	Glass bottle
Raw materials	Bauxite + cryolite	Silica sand + soda + lime
Manufacture	Smelting + rolling + forming	Melting + moulding
Distribution	Lightweight → less fuel	Heavy → more fuel
Use	Single use, recyclable	Often refilled
End of life	95% energy saved on recycling	Refill avoids manufacture

LCAs often reveal that the BEST environmental choice depends on context. A glass bottle that's refilled 25 times beats a single-use can; but a single-use can is better than a glass bottle used only once.

The circular economy. Modern environmental thinking goes beyond recycling to a 'circular economy' — designing products and materials to circulate continuously, not flow once from extraction to landfill. Principles: design for durability, repair, reuse, recycling; share rather than own; turn waste into resource. Many companies (especially in EU + Asia) now commit to circular-economy goals.

Mining vs urban mining. Conventional mining digs ore from the ground. 'Urban mining' recovers metals from already-built infrastructure — old wiring, demolished buildings, scrap cars, electronic waste. As the easy ores are depleted, urban mining will become increasingly important.

Aluminium recycling saves ~95% energy; copper ~80%; steel ~60-70%.
Advantages: less energy, less mining, conserves ores, less landfill.
Disadvantages: collection + sorting costs, contamination, some items uneconomic.
Life-cycle assessment (LCA) compares full environmental impact, raw materials to disposal.
Circular economy: design products to circulate, not be discarded.

See the full worked example for extraction and uses of metals →

How it’s examined

Extraction and uses of metals appears on EVERY Paper 1 (4CH1/1C) and most Paper 2 sittings — worth 10-15 marks per session combined. Paper 1 items: (a) explain why a particular extraction method is used (3-5 marks); (b) blast furnace reactions and equations (5-6 marks); (c) aluminium electrolysis with half-equations + cryolite role (5-6 marks); (d) link metal properties to specific uses (3-5 marks). Paper 2 items: (e) compare environmental impacts of extracting vs recycling (5-6 marks); (f) life-cycle assessment for a specific product (4-6 marks); (g) full account of aluminium production including economics (6-8 marks). The four blast-furnace equations are heavily-tested — memorise all four.

Sources: Pearson Edexcel International GCSE Chemistry 4CH1 specification — Issue 4, September 2024 (valid for 2026 onwards); Pearson Edexcel 4CH1 Examiner Reports 2022-2024; 4CH1/1C May/Jun 2024 question paper and mark scheme; 4CH1/1C January 2024 question paper and mark scheme; 4CH1/1CR January 2024 question paper and mark scheme; 4CH1/2C May/Jun 2024 question paper and mark scheme; 4CH1/2C January 2024 question paper and mark scheme. Last reviewed 2026-05-12.

Master this Topic

Worked examples, formulae, definitions and the mistakes examiners flag — everything you need to push from a pass to an A*.

Take this whole topic with you

Download a branded revision sheet — worked examples, formulae, definitions and common mistakes for Extraction and Uses of Metals, ready to print or save as PDF.

Step-by-step worked examples — Extraction and Uses of Metals

Step-by-step solutions to past-paper-style questions on extraction and uses of metals, written exactly the way a tutor would explain them at the board.

1Explain why different metals are extracted differently (5 marks, Paper 1)
Core• Adapted from 4CH1/1C Jan 2024 Q5• metal extraction, reactivity series, carbon reduction, electrolysis, spec-2.22, spec-2.23
Question
Aluminium and iron are both extracted from their ores on an industrial scale. Aluminium is extracted by electrolysis but iron is extracted by reduction with carbon. (a) Explain why a different extraction method is used for each metal. (b) State why gold is NOT extracted by either method. (5 marks)
Step-by-step solution
1. Step 1
  Position in the reactivity series (1 M). K > Na > Ca > Mg > Al > (C) > Zn > Fe > (H) > Cu > Ag > Au. Aluminium sits ABOVE carbon; iron sits BELOW carbon.
2. Step 2
  (a) Why Al by electrolysis (1 A). Aluminium is MORE reactive than carbon. Carbon CANNOT reduce Al₂O₃ — Al holds onto its oxide ion (O²⁻) more strongly than carbon does. So we must use a more powerful reduction: ELECTROLYSIS forces electrons onto Al³⁺ ions using electrical energy.
3. Step 3
  (a) Why Fe by carbon reduction (1 A). Iron is LESS reactive than carbon. Carbon CAN reduce Fe₂O₃ — carbon attracts oxygen more strongly than iron does. So a hot blast furnace (carbon + iron ore + limestone) is enough to extract iron, much more CHEAPLY than electrolysis.
4. Step 4
  (a) Cost factor (1 B). Electrolysis requires huge amounts of electrical energy (tens of kJ per gram of Al). Carbon reduction needs only heat. So we use the cheaper method whenever the metal allows it (i.e. whenever it's below C in the series).
5. Step 5
  (b) Gold — found native (1 B). Gold is so UNREACTIVE (lowest in the series) that it does NOT form compounds easily — it occurs in nature as the FREE element (native gold nuggets, or fine flakes in rock). It just needs PHYSICAL separation (panning, crushing, chemical leaching) — no chemical extraction needed.
Answer
(a) Al is ABOVE C in the reactivity series → C cannot reduce Al₂O₃; electrolysis required. Fe is BELOW C → C can reduce Fe₂O₃ in a blast furnace, far cheaper than electrolysis. (b) Gold is the LEAST reactive metal — it occurs NATIVE (uncombined) in nature, so only physical separation is needed, not chemical extraction.
Examiner tip
Edexcel 5-mark mark scheme: 1 for reactivity series positions; 1 for Al > C; 1 for Fe < C; 1 for cost / energy argument; 1 for gold being native (or 'unreactive, found in elemental form'). Key examiner phrase: 'metals MORE reactive than carbon CANNOT be extracted by carbon reduction'.
2Aluminium electrolysis — apparatus, equations and cryolite (6 marks, Paper 1)
Core• Adapted from 4CH1/1CR Jan 2024 Q8• aluminium, electrolysis, cryolite, half-equations, spec-2.26, spec-2.27
Question
Aluminium is extracted from purified aluminium oxide (Al₂O₃) by electrolysis. (a) State why cryolite is added to the molten aluminium oxide. (b) Write the half-equations at the cathode and the anode. (c) State the type of reaction (oxidation/reduction) at each electrode. (d) Explain why the carbon anodes need to be replaced periodically. (6 marks)
Step-by-step solution
1. Step 1
  (a) Role of cryolite (1 A). Cryolite (Na₃AlF₆) is added to Al₂O₃ as a SOLVENT. It LOWERS the melting point of the mixture from ~2050 °C (pure Al₂O₃) to ~950 °C. This SAVES ENERGY and makes the process economic — without cryolite, the cost of maintaining the cell at 2050 °C would make the whole process unviable.
2. Step 2
  (b) Cathode half-equation (1 A). Al³⁺ cations migrate to the negative cathode (carbon lining of the cell) and are REDUCED:
  $\text{Al}^{3+} + 3e^- \rightarrow \text{Al}$
3. Step 3
  (b) Anode half-equation (1 A). O²⁻ anions migrate to the positive anode (carbon blocks dipped in) and are OXIDISED. Balance the electrons: each O²⁻ loses 2 e⁻, so 2 O²⁻ together release 4 e⁻ and form one O₂:
  $2\text{O}^{2-} \rightarrow \text{O}_2 + 4e^-$
4. Step 4
  (c) Type of reaction (1 A). Cathode: REDUCTION (gain of electrons / formation of metal from cation). Anode: OXIDATION (loss of electrons / formation of element from anion). Mnemonic: RED CAT (Reduction at Cathode), AN OX (Anode is Oxidation).
5. Step 5
  (d) Anode wears away — reaction with O₂ (1 B). The anode is made of CARBON (graphite). At ~950 °C and in the presence of the O₂ being evolved, hot carbon reacts with oxygen:
  $\text{C(s)} + \text{O}_2\text{(g)} \rightarrow \text{CO}_2\text{(g)}$
6. Step 6
  (d) Consequence — periodic replacement (1 B). The anode is GRADUALLY EATEN AWAY as it is converted to CO₂ (and some CO). It gets thinner over weeks of operation and must be REPLACED REGULARLY. The cost of replacement carbon anodes is a major running cost of aluminium production.
Answer
(a) Cryolite lowers the melting point of Al₂O₃ from ~2050 °C to ~950 °C, saving energy. (b) Cathode: Al³⁺ + 3e⁻ → Al. Anode: 2O²⁻ → O₂ + 4e⁻. (c) Cathode = reduction; Anode = oxidation. (d) Hot carbon anode reacts with O₂ produced: C + O₂ → CO₂. Carbon anode is eaten away → must be replaced.
Examiner tip
Edexcel 6-mark mark scheme: 1 for cryolite lowering mp; 1 each for the two correct half-equations (with balanced electrons!); 1 for reduction/oxidation labels; 1 for C + O₂ → CO₂; 1 for anode burned away/replaced. Common error: missing the '4e⁻' in 2O²⁻ → O₂ + 4e⁻ (because each O²⁻ has charge 2−, total 4).
3Reactions in the blast furnace (6 marks, Paper 1)
Core• Adapted from 4CH1/1C May/Jun 2024 Q8• iron, blast furnace, carbon reduction, spec-2.28, spec-2.29
Question
Iron is extracted from haematite (Fe₂O₃) in a blast furnace using coke, limestone and a blast of hot air. (a) Write balanced equations for the FOUR main reactions that occur. (b) State the function of (i) the limestone, (ii) the slag. (6 marks)
Step-by-step solution
1. Step 1
  Reaction 1 — combustion of coke (1 A). Hot air is blasted into the bottom of the furnace. Coke (impure carbon) burns to give CO₂ and a LOT of heat. The temperature near the bottom reaches ~2000 °C.
  $\text{C(s)} + \text{O}_2\text{(g)} \rightarrow \text{CO}_2\text{(g)}$
2. Step 2
  Reaction 2 — CO₂ reduced to CO (1 A). The CO₂ rises through more hot coke and is REDUCED to carbon monoxide:
  $\text{CO}_2\text{(g)} + \text{C(s)} \rightarrow 2\text{CO(g)}$
3. Step 3
  Reaction 3 — main extraction step: CO reduces Fe₂O₃ (1 A). The CO is the actual reducing agent. It rises and meets the iron ore Fe₂O₃, reducing it to molten iron:
  $\text{Fe}_2\text{O}_3\text{(s)} + 3\text{CO(g)} \rightarrow 2\text{Fe(l)} + 3\text{CO}_2\text{(g)}$
4. Step 4
  Reaction 4 — limestone decomposes (1 A). CaCO₃ (limestone) decomposes in the heat to give CaO:
  $\text{CaCO}_3\text{(s)} \rightarrow \text{CaO(s)} + \text{CO}_2\text{(g)}$
5. Step 5
  (b)(i) Function of limestone (1 B). Limestone decomposes to give CaO. The CaO (calcium oxide) is a BASE that reacts with the ACIDIC silica (SiO₂) impurity in the iron ore. The silica would otherwise contaminate the iron:
  $\text{CaO(s)} + \text{SiO}_2\text{(s)} \rightarrow \text{CaSiO}_3\text{(l) (slag)}$
6. Step 6
  (b)(ii) Function of slag (1 B). The calcium silicate (CaSiO₃) — known as slag — is a molten liquid that FLOATS on top of the denser molten iron. It can be tapped off separately. Slag REMOVES the silica IMPURITIES from the iron, giving cleaner iron product. Slag is sold for road-building, fertiliser and breeze blocks (not waste!).
Answer
(a) 1. C + O₂ → CO₂; 2. CO₂ + C → 2CO; 3. Fe₂O₃ + 3CO → 2Fe + 3CO₂ (main step); 4. CaCO₃ → CaO + CO₂. (b)(i) Limestone decomposes to give CaO, which reacts with SiO₂ impurity: CaO + SiO₂ → CaSiO₃. (ii) Slag (CaSiO₃) floats on molten iron, removing silica impurities; tapped off separately and used in road construction.
Examiner tip
Edexcel 6-mark mark scheme: 4 marks for the four balanced equations (1 each); 1 for function of limestone (decomposes; CaO reacts with silica); 1 for function of slag (floats on Fe, removes silica). Common error: writing 'C reduces Fe₂O₃ directly' — the actual reducing agent is CO, not C. Carbon is the source of CO via the C + CO₂ → 2CO reaction.
4Advantages of recycling aluminium (6 marks, Paper 2)
Extended• Adapted from 4CH1/2C May/Jun 2024 Q4• recycling, aluminium, sustainability, spec-2.33, spec-2.34
Question
It is estimated that recycling aluminium uses only ~5% of the energy needed to extract it from bauxite. (a) Identify FOUR environmental or economic advantages of recycling aluminium. (b) State TWO disadvantages or limitations of recycling. (c) Suggest why aluminium cans are more commonly recycled than aluminium foil. (6 marks)
Step-by-step solution
1. Step 1
  (a) Advantage 1 — energy saving (1 A). Electrolysis of bauxite is extremely energy-intensive (~14 MWh per tonne of Al). Recycling melts and re-casts existing aluminium, using only ~5% of the energy. This DIRECTLY reduces fossil-fuel consumption + CO₂ emissions from power generation.
2. Step 2
  (a) Advantage 2 — conservation of bauxite (1 A). Bauxite is a FINITE natural resource — extraction depletes the ore reserves. Recycling reduces the rate at which we use up this finite resource.
3. Step 3
  (a) Advantage 3 — less mining (1 A). Mining bauxite damages landscapes (deforestation, loss of biodiversity, soil erosion, polluted run-off, dust). Less mining → less environmental damage.
4. Step 4
  (a) Advantage 4 — less waste / less landfill (1 A). Aluminium does not biodegrade; in landfill it persists for hundreds of years. Recycling diverts cans/foil from landfill, reducing landfill pressure.
5. Step 5
  (b) Disadvantage 1 (1 B). Collection, transport and sorting of recyclable aluminium has costs (energy for trucks, labour, sorting facilities). If poorly managed, the carbon footprint of collection can offset some recycling gains.
6. Step 6
  (b) Disadvantage 2 + (c) cans vs foil (1 B). Aluminium foil is thin and lightweight — the cost of collecting and sorting it can exceed the value recovered. Foil is often CONTAMINATED with food residues, paint or plastic, making it harder to recycle. Cans, by contrast, are heavier, easier to identify, separable by magnet (Al ≠ steel), and have less food contamination. Hence cans are more commonly recycled.
Answer
(a) FOUR advantages: (1) 95% energy saving (less fossil fuel, less CO₂); (2) conserves finite bauxite ore; (3) less mining → less habitat destruction; (4) reduces landfill / non-biodegradable waste. (b) Disadvantages: (1) cost of collection + sorting; (2) contamination from labels, food, paint; (3) foil too thin/light to be cost-effective. (c) Cans recycled more often because thicker, more valuable per item, easier to separate, less contaminated. Foil too thin and often dirty.
Examiner tip
Edexcel 6-mark mark scheme: 4 marks for any four valid advantages (energy / bauxite / mining / landfill / CO₂); 2 marks for valid disadvantages or the cans-vs-foil reason. Always include the 95% (~14×) energy saving — examiners look for this specific figure.
5Compare uses of pure copper and brass; explain alloying (5 marks, Paper 1)
Core• Adapted from 4CH1/1CR May/Jun 2024 Q6• alloys, uses of metals, brass, copper, spec-2.32
Question
Pure copper is used for electrical wiring; brass (an alloy of copper and zinc) is used for door handles and musical instruments. (a) Explain why pure copper is preferred for wiring. (b) Explain how alloying with zinc changes the properties of copper, and why this is useful for door handles. (c) State ONE other common copper-based alloy and one of its uses. (5 marks)
Step-by-step solution
1. Step 1
  (a) Properties of pure copper for wiring (1 A). Pure copper is a SOFT, MALLEABLE, DUCTILE metal. Most importantly, it has VERY HIGH electrical conductivity (only silver is better, and silver is too expensive). Ductility means it can be drawn into long thin wires without breaking. Malleability means it can be bent and shaped easily.
2. Step 2
  (a) Why purity matters (1 B). Impurities scatter the conduction electrons → impurities INCREASE electrical resistance. For long power cables, even small impurities cause significant power losses. Hence pure copper (purified by electrolysis from blister copper) is the standard for wiring.
3. Step 3
  (b) Brass — properties and changes (1 A). Brass is an alloy of copper (~70%) + zinc (~30%). Adding zinc atoms (different size) disrupts the regular copper crystal lattice, so layers of atoms cannot slide as easily under stress. Brass is HARDER and STRONGER than pure copper; but it RETAINS the corrosion resistance of copper and an attractive golden-yellow appearance.
4. Step 4
  (b) Why brass for door handles (1 B). A door handle gets touched and twisted thousands of times. Pure copper would be too soft → deforms and scratches. Brass is hard enough to resist wear, attractive, antibacterial (kills surface microbes), and corrosion-resistant. Same logic applies to musical instruments (trumpets) — brass holds its shape AND is acoustically resonant.
5. Step 5
  (c) Bronze — copper + tin (1 B). Bronze is an alloy of copper + tin. It is harder than pure copper, corrosion-resistant in seawater, and has been used for thousands of years for bells, statues, propellers, coins, and ancient tools/weapons (the 'Bronze Age'). Examples accepted: bronze for ships' propellers, sculpture, or musical instruments (gongs and bells).
Answer
(a) Pure Cu is highly conductive (impurities raise resistance) and ductile/malleable — drawn into wires. (b) Brass = Cu + Zn. Zinc atoms disrupt the Cu lattice, layers can't slide → brass is HARDER and STRONGER than pure Cu, but keeps Cu's corrosion resistance and golden appearance. Hard enough for handles that get heavy use. (c) Bronze = Cu + Sn. Uses: ship propellers, statues, bells, gongs, coins.
Examiner tip
Edexcel 5-mark mark scheme: 1 for pure Cu = conductive + ductile; 1 for impurities raising resistance; 1 for brass = Cu + Zn AND being harder; 1 for the lattice disruption explanation (layers can't slide); 1 for bronze (Cu + Sn) with use. Always link the property to the use — examiners want 'X is hard because... → therefore used for Y'.

Model Answers — Extraction and Uses of Metals

High-scoring sample answers for extraction and uses of metals on the Pearson Edexcel IGCSE 4CH1 paper, with examiner-style notes mapping each response to the mark scheme and assessment objectives.

Question 1

4CH1/2C-style — extraction method choice6 marks

Using the reactivity series K, Na, Ca, Mg, Al, (C), Zn, Fe, (H), Cu, Ag, Au, explain how the choice of extraction method depends on a metal's position. Cite three metals at different positions to illustrate. (6 marks)

Model answer

The reactivity series tells us how strongly a metal holds onto its compounds (oxides, sulfides, halides). The more reactive the metal, the more tightly it binds — hence the more energetic the extraction method needed.

Three categories based on position relative to carbon and the inert metals.

Position	Examples	Method	Why
ABOVE carbon	K, Na, Ca, Mg, Al	Electrolysis of MOLTEN ore	C cannot reduce these — too reactive
BELOW carbon and ABOVE H	Zn, Fe, Sn, Pb	Reduction with C / CO	C can reduce these oxides; cheaper than electrolysis
BELOW H (native metals)	Cu (partly), Ag, Au, Pt	Found native or simple chemical separation	So unreactive they exist as free element

Example 1 — Aluminium (ABOVE carbon). Method: electrolysis.

Aluminium is more reactive than carbon → carbon cannot reduce Al₂O₃. We must use the more powerful reduction of ELECTROLYSIS.

Procedure: dissolve purified Al₂O₃ in molten cryolite (Na₃AlF₆) to lower the melting point from ~2050 °C to ~950 °C. Pass a very large DC current through the molten mixture using carbon electrodes.

Cathode: Al³⁺ + 3e⁻ → Al (molten metal collects at the bottom and is tapped off).
Anode: 2O²⁻ → O₂ + 4e⁻ (oxygen evolved; hot carbon anode reacts: C + O₂ → CO₂, so anodes must be replaced regularly).

Aluminium production is energy-intensive and EXPENSIVE — but it's the only viable method for this metal.

Example 2 — Iron (BELOW carbon). Method: reduction with C/CO in a blast furnace.

Iron is less reactive than carbon → C can reduce Fe₂O₃ (haematite). The hot blast furnace runs continuously, with charge added at the top and molten iron tapped from the bottom.

Key reactions:

C + O₂ → CO₂ (combustion of coke — heat source).
CO₂ + C → 2CO (carbon dioxide reduced to CO — the actual reducing agent).
Fe₂O₃ + 3CO → 2Fe + 3CO₂ (main reduction — iron extracted).
CaCO₃ → CaO + CO₂ (limestone decomposes).
CaO + SiO₂ → CaSiO₃ (slag — removes silica impurities; slag floats and is tapped off).

Iron extraction by blast furnace is far cheaper than electrolysis would be — hence ~95% of iron used worldwide is made this way.

Example 3 — Gold (BELOW hydrogen, almost inert). Method: native; physical separation.

Gold is the least reactive common metal. It does NOT readily oxidise, does not dissolve in water/acid (except aqua regia), and does not form compounds easily. Hence gold occurs in nature as the FREE ELEMENT — small nuggets in alluvial deposits and quartz veins.

To 'extract' gold, we only need physical methods:

Panning: gravel and sand washed with water; dense gold sinks while lighter material floats away.
Cyanide leaching: dissolves gold from crushed rock as a complex ion; precipitated and refined.
Electrorefining: final purification by electrolysis with a gold cathode.

No 'chemical' extraction from an ore is needed because gold isn't in a compound to begin with.

Other valid examples (for reference):

Copper: traditionally extracted by reduction of CuO with carbon (CuO + C → Cu + CO). Modern method: smelting copper sulfide ores, then electrolytic refining for ≥ 99.99% purity needed for wiring.
Zinc: extracted by carbon reduction of ZnO at high temperature.
Sodium: extracted by electrolysis of molten NaCl (Downs cell — used industrially since 1924).

Summary rule. "Reactivity above carbon → electrolysis. Below carbon → carbon reduction. Below hydrogen and very unreactive → found native."

Why this scores

Edexcel 6-mark mark scheme: 2 marks for 'method depends on reactivity / position relative to carbon'; 2 marks for two correctly-described extraction methods (electrolysis for Al, carbon reduction for Fe); 1 mark for native gold; 1 mark for cost/energy justification. Always link the method to the metal's reactivity position.

Question 2

4CH1/1CR-style — metals and uses6 marks

Justify the choice of metal for each of the following everyday uses by linking the property required to the metal's behaviour: (i) aluminium for aircraft bodies; (ii) copper for electrical wiring; (iii) iron alloyed with chromium for surgical instruments; (iv) iron for car body panels. (6 marks)

Model answer

Each engineering choice balances strength, density, corrosion resistance, cost and recyclability. The property requirements differ from application to application.

(i) Aluminium for aircraft bodies.

Required properties: LOW DENSITY (so the plane can fly economically), STRONG (especially in alloys like duralumin), CORROSION-RESISTANT (otherwise the aircraft would rust in moist air).

Aluminium density ~2.70 g/cm³ vs steel ~7.87 g/cm³ — Al is about 1/3 the density of steel. A lighter aircraft uses LESS FUEL for the same payload.
Pure aluminium is soft, but alloyed with copper, magnesium and manganese (duralumin) it becomes as strong as mild steel.
Aluminium forms a thin tough layer of Al₂O₃ on its surface that prevents further oxidation — so it doesn't 'rust away' in moist air or salt spray.

(ii) Copper for electrical wiring.

Required properties: HIGH electrical conductivity, DUCTILE (drawn into wires), MALLEABLE (bent and shaped without breaking), reasonably PRICED (silver is better but too expensive).

Copper has the second-highest electrical conductivity of all metals (after silver), so power losses in wires are small.
Copper is highly ductile — can be drawn into thin wires (kilometres long) without snapping.
Pure copper is essential — impurities scatter conduction electrons and increase resistance. Copper is purified by electrolysis to ≥ 99.99% before being used for wiring.

(iii) Iron alloyed with chromium (stainless steel) for surgical instruments.

Required properties: CORROSION-RESISTANT (no rust on a sterile instrument), HARD enough to keep a sharp edge, BIOCOMPATIBLE (doesn't react with body fluids), STERILISABLE (can withstand repeated autoclaving).

Stainless steel is iron alloyed with ~18% chromium and ~8% nickel. The chromium forms a thin protective Cr₂O₃ layer that prevents the iron beneath from rusting — even when exposed to body fluids, blood and saline.
Hardness comes from the alloy structure (Cr and Ni atoms disrupt the iron lattice → harder to deform). Surgical scalpels keep their sharpness.
Sterilisation: stainless steel withstands high temperature and pressure in autoclaves (>120 °C, steam) without corroding.
Compare with pure iron: would rust quickly, blunt with use, react with body fluids — unsuitable for surgery.

(iv) Iron for car body panels.

Required properties: STRONG (must withstand impact, hold shape), CHEAP (cars are mass-produced), MALLEABLE (pressed into shape), RECYCLABLE.

Mild steel (Fe + 0.1-0.3% C) is much stronger than pure iron — carbon atoms 'pin' the iron lattice so it doesn't deform plastically.
Steel is cheap to produce in vast quantities (blast furnace + basic oxygen process). About 1.5 tonnes per car worldwide.
Steel is malleable when hot — can be pressed into complex shapes like fenders, doors, roofs.
Steel is highly recyclable (magnetic, easy to separate). About 60% of new steel is from scrap.

Limitation: steel rusts, so car bodies must be PAINTED or galvanised. Modern cars use galvanised steel + multiple paint layers + sacrificial anode in the chassis to combat rust.

Summary table — property to use.

Use	Required property	Metal/alloy chosen	Why
Aircraft	Low density + strength + corrosion-resistant	Al alloy (duralumin)	1/3 density of steel; oxide layer protects
Wiring	Conductivity + ductility	Pure Cu	2nd-highest conductivity; drawn into wires
Surgical instruments	Corrosion + hardness + sterilisable	Stainless steel (Fe+Cr+Ni)	Cr₂O₃ layer; alloy hardness; autoclavable
Car bodies	Strong + cheap + malleable + recyclable	Mild steel (Fe+C)	Inexpensive, strong, pressed into shape

Why this scores

Edexcel 6-mark mark scheme: 1.5 marks per part = 6 total. For each part: 1 for stating the relevant property; 0.5 for linking to the metal's behaviour. Always pair the use with the SPECIFIC property (not generic 'because it's strong'). Examiners want 'low density allows fuel-efficient flight' rather than 'aluminium is good'.

Question 3
4CH1/2C-style — blast furnace operation6 marks
Describe the operation of a blast furnace used to extract iron from haematite. Include the raw materials, the location and function of each, the four key chemical reactions, and the role of slag. Why does the furnace operate continuously rather than in batches? (6 marks)
Model answer
Raw materials. Three solid raw materials are charged into the top of the furnace continuously:

Iron ore — usually haematite, Fe₂O₃, sometimes magnetite Fe₃O₄.

Coke — refined coal, mostly carbon. Provides both the heat (combustion) and the reducing agent (CO).

Limestone — calcium carbonate, CaCO₃. Removes the silica impurity in the ore.

A blast of hot air (~1200 °C) is blown in near the bottom of the furnace through nozzles called 'tuyères'. The whole structure is a tall tower (40+ metres) lined with refractory bricks.

Operating conditions and reaction zones.

Bottom (hottest, ~2000 °C): combustion of coke + reduction.

Middle (~1000-1500 °C): main reduction of iron ore.

Top (~200-700 °C, cooler): limestone decomposes.

Four key reactions.

Reaction 1 — Combustion of coke (highly exothermic).

$\text{C(s)} + \text{O}_2\text{(g)} \rightarrow \text{CO}_2\text{(g)}$

This is the primary heat source. The hot air blast supplies the O₂.

Reaction 2 — Reduction of CO₂ to CO (endothermic).

$\text{CO}_2\text{(g)} + \text{C(s)} \rightarrow 2\text{CO(g)}$

The CO₂ produced in Reaction 1 rises and meets more hot coke. CO is formed — the ACTUAL REDUCING AGENT for the iron ore.

Reaction 3 — Main extraction: CO reduces iron ore.

$\text{Fe}_2\text{O}_3\text{(s)} + 3\text{CO(g)} \rightarrow 2\text{Fe(l)} + 3\text{CO}_2\text{(g)}$

This is the key reaction. CO is oxidised (loses electrons → CO₂); Fe³⁺ is reduced (gains electrons → Fe). The molten iron drains to the bottom of the furnace.

Reaction 4 — Thermal decomposition of limestone.

$\text{CaCO}_3\text{(s)} \rightarrow \text{CaO(s)} + \text{CO}_2\text{(g)}$

At the higher levels of the furnace, limestone breaks down. The CaO is needed for the next step.

Removal of silica impurities — slag formation.

Iron ore contains silica (sand, SiO₂) as an acidic impurity. CaO is a base, so it reacts with the acidic silica:

$\text{CaO(s)} + \text{SiO}_2\text{(s)} \rightarrow \text{CaSiO}_3\text{(l)}$

The product, calcium silicate (CaSiO₃), is known as SLAG. It is a molten liquid LESS DENSE than molten iron, so it floats on top of the iron layer at the bottom. Slag can be tapped off SEPARATELY from the iron through a different hole.

Slag is sold for road-building (aggregate), fertiliser ingredients and breeze blocks — it is NOT waste.

Why the furnace is operated continuously.

Heating up costs a lot of energy. The furnace lining and contents take days to heat up to operating temperature. Cooling and reheating wastes huge energy.

Thermal stress on the lining. Each heating/cooling cycle stresses the refractory bricks → cracks → expensive repairs. Continuous operation keeps the lining at constant temperature.

Throughput economy. A typical blast furnace produces ~10,000 tonnes of iron per day. Continuous operation maximises this throughput.

So in practice, a blast furnace runs 24/7/365 for 5-15 years between major rebuilds (called 'campaigns'). Raw materials are added continuously at the top, hot gas blown in at the bottom, and iron + slag tapped at the bottom every few hours.

Products tapped off.

Molten iron (called 'pig iron') — ~96% iron, ~4% carbon and other impurities. Sent to a Basic Oxygen Furnace to refine into steel.

Slag — calcium silicate; sold for construction.

Waste gases (CO₂, CO, N₂) — cleaned and used to pre-heat the incoming air ('regenerative heating').
Why this scores
Edexcel 6-mark mark scheme: 3 marks for the four equations (in correct order); 1 mark for slag and its role; 1 mark for why continuous operation (heating cost OR thermal stress); 1 mark for raw materials (coke, ore, limestone). Common error: writing 'C reduces Fe₂O₃' directly. The actual reducing agent in the main extraction step is CO.
Question 4
4CH1/2C-style — environmental impact of metals6 marks
Compare the environmental impacts of (i) extracting copper from its ore versus (ii) recycling copper. Suggest THREE practical actions a country can take to reduce the overall environmental cost of metal use. (6 marks)
Model answer
Copper is a vital metal for the modern economy (electrical wiring, plumbing, electronics). Demand is high and growing — particularly for renewable-energy infrastructure (wind turbines, solar farms, electric vehicles). But primary extraction has heavy environmental costs.

Environmental impacts of extracting copper from ore.

Land disturbance from open-pit mining. Copper ore (often only 0.5-2% Cu) requires moving enormous quantities of rock to expose the ore body. The Bingham Canyon mine in Utah is the largest man-made excavation on Earth. Pits leave permanent scars on the landscape, destroy habitats, displace communities.

Energy intensity. Crushing, grinding, smelting and electrolytic refining of low-grade ore is highly energy-intensive — ~10 GJ of energy per tonne of refined copper. Most of this energy comes from fossil fuels → significant CO₂ emissions.

Air pollution. Smelting copper sulfide ores releases SO₂ (Cu₂S + O₂ → Cu + SO₂). Without scrubbers, this contributes to acid rain. Modern smelters capture most SO₂ but historic operations caused severe local pollution.

Water pollution. Acidic mine drainage — sulfide minerals exposed to air + water produce sulfuric acid, which dissolves heavy metals (Cu, Zn, Cd) into local water systems. Persists for centuries after the mine closes.

Tailings (mine waste). Vast volumes of finely ground rock waste, often containing toxic chemicals from processing (cyanide, xanthates). Tailings dams can fail (e.g. Brumadinho, Brazil, 2019).

Environmental impacts of recycling copper.

Much lower energy. Recycling copper uses only ~15-20% of the energy needed for primary extraction (lower than aluminium's 95% saving, but still very significant).

No new mining. Conserves the finite ore deposits and avoids the land-disturbance impacts above.

Reduced air/water pollution. No SO₂ emissions; no acidic mine drainage; no tailings.

Less waste in landfill. Recovered copper from old wiring, plumbing, electronics doesn't go to landfill.

Limitations of recycling.

Sorting and processing scrap has its own carbon footprint (transport, separation, melting).

Some applications (electronics) contain copper in such tiny quantities that recovery isn't economic.

Quality must be controlled — impurities in scrap can affect product quality.

THREE practical actions to reduce environmental cost.

1. Increase recycling rates. Government incentives, mandatory recycling for specific products (electronics, vehicles), kerbside collection of household scrap. EU 'Right to Repair' legislation forcing manufacturers to design for disassembly and recycling.

2. Improve product longevity / circular design. Design products to last longer, be modular and repairable, and easy to disassemble at end-of-life. 'Cradle-to-cradle' design ensures materials flow back into new products rather than waste.

3. Use renewable energy in smelting/refining. If the necessary primary extraction is powered by solar, wind or hydro (rather than coal), the CO₂ footprint drops dramatically. Switzerland, Norway and Iceland have low-carbon aluminium and copper industries.

Other valid actions. Substitute with less-impactful materials where possible (e.g. aluminium wiring for some applications, fibre-optic instead of copper data cables); tax virgin materials more heavily than recycled; develop better mining technologies (bioleaching uses bacteria to dissolve copper at low energy); urban mining (recovering metals from old infrastructure).

The big picture. Recycling is part of a wider 'circular economy' — keeping materials in use as long as possible, recovering them at end-of-life, and only mining new resources to top up shortfalls. As global metal demand keeps rising, recycling will become increasingly important.
Why this scores
Edexcel 6-mark mark scheme: 2 for environmental impacts of primary extraction (any from: land use, energy, air pollution, water pollution, waste); 2 for benefits of recycling (energy saving, less mining, less waste); 2 for valid mitigation actions (any reasonable answer linked to less use, more recycling, or renewable energy). High-band answers connect specific impacts to specific solutions.

Key Definitions and Keywords — Extraction and Uses of Metals

Definitions to memorise and the exact keywords mark schemes credit for extraction and uses of metals answers — sharpened from recent examiner reports for the 2026 Pearson Edexcel IGCSE 4CH1 sitting.

Ore
Examiner keyword
A naturally occurring rock or mineral containing a metal compound in high enough concentration to make extraction economic. Examples: haematite (Fe₂O₃), bauxite (Al₂O₃·2H₂O), chalcopyrite (CuFeS₂).
Extraction (of a metal)
Examiner keyword
The chemical process of separating a metal from its naturally occurring compound (the ore). Method depends on the metal's position in the reactivity series: electrolysis for above-C metals; carbon reduction for below-C metals; physical separation for native metals.
Bauxite
Examiner keyword
The main ore of aluminium — a hydrated aluminium oxide (Al₂O₃·2H₂O) with impurities of iron oxide and silica. Purified to give Al₂O₃ before electrolysis.
Haematite
Examiner keyword
The main ore of iron — mainly iron(III) oxide, Fe₂O₃. Reduced to iron in the blast furnace using carbon monoxide.
Cryolite
Examiner keyword
Sodium hexafluoroaluminate, Na₃AlF₆. Added to Al₂O₃ during aluminium electrolysis as a SOLVENT. Lowers the melting point of the mixture from ~2050 °C to ~950 °C, saving energy.
Blast furnace
Examiner keyword
A tall industrial furnace used to extract iron from iron ore by reduction with carbon. Charged at the top with iron ore (Fe₂O₃), coke (C), and limestone (CaCO₃); hot air blasted in at the bottom. Operates continuously.
Slag
Examiner keyword
Calcium silicate (CaSiO₃) — a molten liquid formed in the blast furnace when CaO (from limestone) reacts with silica (SiO₂) impurities in the iron ore. Floats on the denser molten iron and is tapped off separately. Sold for road-building and breeze blocks.
Coke
Examiner keyword
Almost pure carbon, made by heating coal in the absence of air. Used in the blast furnace as both a fuel (combustion provides heat) and a reducing agent (produces CO via C + CO₂ → 2CO).
Alloy
Examiner keyword
A mixture of a metal with one or more other elements (usually metals or carbon). Designed to have different properties from the pure metal — typically harder, stronger, or more corrosion-resistant. Examples: brass (Cu + Zn), bronze (Cu + Sn), steel (Fe + C), stainless steel (Fe + Cr + Ni).
Native metal
Examiner keyword
A metal that occurs in nature as the FREE ELEMENT (not in a compound). Limited to the most unreactive metals: gold, silver, platinum, and sometimes copper. Extracted by physical methods only.
Recycling
Examiner keyword
Collecting used metal items (cans, scrap, electronics) and processing them back into new products. Saves energy (e.g. 95% for aluminium, ~80% for copper), conserves finite ores, and reduces landfill and pollution.

Common Mistakes and Misconceptions — Extraction and Uses of Metals

The traps other students keep falling into on extraction and uses of metals questions — taken from recent Pearson Edexcel IGCSE 4CH1 examiner reports and mark schemes — and how to avoid them.

✕Writing 'C reduces Fe₂O₃' as the main blast furnace reduction step
4CH1 Examiner Reports 2022-2024
Why it happens
Knowing that the furnace 'uses carbon to reduce iron ore'.
How to avoid it
The ACTUAL reducing agent is CO, not C. The reaction sequence is: (1) C + O₂ → CO₂ (combustion); (2) CO₂ + C → 2CO (CO formation); (3) Fe₂O₃ + 3CO → 2Fe + 3CO₂ (MAIN reduction). Write all three to get full marks.
✕Stating that cryolite REACTS with Al₂O₃ to form aluminium
4CH1 Examiner Reports 2023-2024
Why it happens
Confusing solvent with reactant.
How to avoid it
Cryolite is a SOLVENT — it dissolves Al₂O₃ to lower the operating temperature. It is NOT a reactant; it is RECOVERED unchanged after the electrolysis. The ions discharged at the electrodes are Al³⁺ and O²⁻ from Al₂O₃, not from cryolite.
✕Writing the half-equations backwards in aluminium electrolysis
Why it happens
Confusing which electrode is which.
How to avoid it
Cathode (NEGATIVE) attracts CATIONS (positive) — Al³⁺ → Al. Anode (POSITIVE) attracts ANIONS (negative) — O²⁻ → O₂. Memorise: 'PANIC — Positive Anode Negative Is Cathode'.
✕Calling slag a 'waste product' of the blast furnace
Why it happens
Confusing it with the actual waste gases.
How to avoid it
Slag is NOT waste — it is sold for road-building (aggregate), breeze blocks and fertiliser ingredients. The actual 'waste' is the gases (CO₂, CO, N₂) that exit the top; these are scrubbed and partly reused.
✕Saying that gold is extracted from a 'gold ore' chemically
4CH1 Examiner Reports 2022-2024
Why it happens
Generalising the metal extraction theme.
How to avoid it
Gold occurs NATIVE — uncombined in nature, as nuggets and flakes. No chemical extraction is needed. Methods are PHYSICAL: panning, crushing, cyanide leaching (which is technically chemical, but produces dissolved Au⁺ that's then precipitated, not from an oxide).
✕Stating that recycling aluminium 'saves 50%' or 'saves 5%' of the energy
Why it happens
Confusing 'uses 5%' (recycling) with 'saves 50%' (a different statistic).
How to avoid it
Recycling Al USES ~5% of the energy of primary extraction → SAVES ~95% of the energy. Many candidates flip these. Memorise: '95% energy saving from recycling Al'.

Practice questions

Exam-style questions with step-by-step worked solutions. Try one before checking the method.

Past paper style quiz

Get a report showing which sub-topics you've nailed and which ones still need work.

Video lesson

Short walkthrough of the concepts students most often get stuck on.

Extraction and Uses of Metals — frequently asked questions

The things students keep getting wrong in this sub-topic, answered.

Extraction and Uses of Metals

Short Study Notes in the form of Slides

Short Study Notes — Extraction and Uses of Metals

Detailed Notes

What you’ll learn

How it’s examined

1Explain why different metals are extracted differently (5 marks, Paper 1)

2Aluminium electrolysis — apparatus, equations and cryolite (6 marks, Paper 1)

3Reactions in the blast furnace (6 marks, Paper 1)

4Advantages of recycling aluminium (6 marks, Paper 2)

5Compare uses of pure copper and brass; explain alloying (5 marks, Paper 1)

Ore

Extraction (of a metal)

Bauxite

Haematite

Cryolite

Blast furnace

Slag

Coke

Alloy

Native metal

Recycling

✕Writing 'C reduces Fe₂O₃' as the main blast furnace reduction step

✕Stating that cryolite REACTS with Al₂O₃ to form aluminium

✕Writing the half-equations backwards in aluminium electrolysis

✕Calling slag a 'waste product' of the blast furnace

✕Saying that gold is extracted from a 'gold ore' chemically

✕Stating that recycling aluminium 'saves 50%' or 'saves 5%' of the energy

Practice questions

Past paper style quiz

Assess your understanding

Video lesson

Extraction and Uses of Metals — frequently asked questions