Metal extraction and resource choices

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Lesson notes

Big idea: metal extraction and resource choices

Key concept: Systems. Metals below carbon in the reactivity series can often be extracted by reduction with carbon. More reactive metals such as aluminium require electrolysis of suitable compounds.
Related concepts: Models and evidence. Use a scientific explanation to make predictions, then test it against observations.
Global context: Scientific and technical innovation. Recycling can reduce demand for fresh ore and extraction energy.

Metals and Ores

The Earth’s crust contains metals and metal compounds.
A metal ore is a rock that contains enough of the metal to make extraction worthwhile.
Many metal ores are oxides (e.g., hematite for iron, bauxite for aluminium).
Extraction is a reduction process because oxygen is removed from the ore.
Very unreactive metals like gold and platinum are found native (as uncombined elements).

Reactivity Series and Extraction Method

The extraction method depends on the metal's position in the reactivity series.
Metals above carbon must be extracted by electrolysis (e.g., aluminium).
Metals below carbon can be extracted by heating with carbon or carbon monoxide (e.g., iron).
Metals lower in the series are easier to extract than those higher up.
Electrolysis uses large amounts of electricity, making it expensive.

Extraction of Iron from Hematite – Blast Furnace

Iron is extracted from its ore hematite (Fe₂O₃) in a blast furnace.
Raw materials: iron ore, coke (impure carbon), and limestone (CaCO₃).
Hot air is blown into the bottom of the furnace.

The blast furnace

Reactions in the Blast Furnace

Zone 1: Coke burns: C + O₂ → CO₂ (exothermic, provides heat).
Zone 2: CO₂ + C → 2CO (carbon monoxide is the main reducing agent).
Zone 3: Fe₂O₃ + 3CO → 2Fe + 3CO₂ (reduction of iron ore).
Limestone decomposes: CaCO₃ → CaO + CO₂ (thermal decomposition).
CaO removes SiO₂ impurity: CaO + SiO₂ → CaSiO₃ (slag).
Molten iron is tapped from the bottom; slag floats on top and is removed separately.

Extraction of Aluminium from Bauxite – Electrolysis

Aluminium is extracted from bauxite (Al₂O₃) by electrolysis.
Aluminium is above carbon in the reactivity series, so carbon reduction is not possible.
Al₂O₃ is dissolved in molten cryolite to lower the melting point (from >2000°C to ~950°C).
The electrolysis cell has a graphite lining (cathode) and graphite anodes.
At cathode: Al³⁺ + 3e⁻ → Al (reduction).
At anode: 2O²⁻ → O₂ + 4e⁻ (oxidation).
Overall: 2Al₂O₃ → 4Al + 3O₂.
Oxygen reacts with the carbon anodes to form CO₂, so anodes wear away and must be replaced.

Electrolysis of aluminium oxide

Explaining and applying the science

Remember OIL RIG: Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons).
For iron extraction, know the three zones and the role of limestone.
For aluminium, explain why cryolite is used and why anodes need replacing.
Unreactive metals (Cu, Ag, Au) may be found native or extracted by simple heating.

Think like a scientist

Use industrial datasets to compare the energy inputs of alternative extraction routes for a specified metal.
Comparison: the extraction route. Outcome: energy used per kilogram of metal produced.
Control: compare the same metal and the same product purity. Explain why this makes the comparison fairer.
Evidence: Use a consistent method, repeated observations where appropriate and a table with labelled quantities and units. Keep unexpected results and investigate their cause.
Safety: Practical activities need teacher supervision and an appropriate risk assessment. Use the provided data or simulation where the investigation specifies it.
Inquiry task: State a testable question, predict the outcome using the science, then explain how your observations would support or challenge the prediction.

Evaluate the science

Recycling can reduce demand for fresh ore and extraction energy.
Compare collection, transport, sorting, purity and energy together; one energy figure is not a complete environmental assessment.
Evaluation task: Link your conclusion to evidence, identify a limitation and suggest a specific improvement. Distinguish a measured result from an explanation of its cause.

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Practice questions

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1.Which of the following is the main ore of aluminium?
Easy
- ABauxite
- BHematite
- CMalachite
- DLimestone
2.Which of the following metals is found native (as the uncombined element) in the Earth's crust?
Easy
- AGold
- BIron
- CAluminium
- DZinc
3.What is the main reducing agent in the blast furnace for the extraction of iron?
Easy
- ACarbon monoxide
- BCarbon dioxide
- CCoke
- DLimestone
4.In the extraction of aluminium by electrolysis, why is aluminium oxide dissolved in molten cryolite?
Medium
- ATo lower the melting point of the mixture
- BTo provide a source of aluminium ions
- CTo act as a reducing agent
- DTo increase the conductivity of the solution
5.In the blast furnace, which substance is added to remove impurities such as silicon dioxide?
Easy
- ALimestone
- BCoke
- CIron ore
- DCarbon monoxide
6.Which of the following statements about transition elements is correct?
Easy
- ATheir compounds are highly coloured
- BThey have low melting points
- CTheir compounds are colourless
- DThey have only one oxidation state
7.The overall equation for the extraction of aluminium is 2Al2O3 → 4Al + 3O2. At the anode, oxygen reacts with the graphite electrodes. What is the main reason the anodes need to be replaced periodically?
Medium
- AThe graphite reacts with oxygen to form CO2, wearing away the anode
- BThe aluminium produced attacks the anode
- CThe cryolite dissolves the graphite
- DThe high temperature melts the graphite
8.In the blast furnace, which reaction is an example of thermal decomposition?
Easy
- ACaCO3 → CaO + CO2
- BC + O2 → CO2
- CCO2 + C → 2CO
- DFe2O3 + 3CO → 2Fe + 3CO2

More questions

9.Which of the following metals is extracted by reduction with carbon?
Easy
- AIron
- BAluminium
- CSodium
- DPotassium
10.Why is aluminium not extracted by reduction with carbon?
Easy
- AAluminium is above carbon in the reactivity series
- BAluminium is too expensive
- CAluminium oxide is not an ore
- DCarbon reacts explosively with aluminium
11.In the electrolysis of aluminium oxide, what is produced at the negative electrode (cathode)?
Easy
- AAluminium
- BOxygen
- CCarbon dioxide
- DCryolite
12.In the blast furnace, the reaction Fe2O3 + 3CO → 2Fe + 3CO2 shows that iron(III) oxide is reduced. What is the reducing agent?
Easy
- ACarbon monoxide
- BIron(III) oxide
- CIron
- DCarbon dioxide
13.In a blast furnace, the reaction CaCO3 → CaO + CO2 occurs. Which type of reaction is this?
Easy
- AThermal decomposition
- BCombustion
- CReduction
- DOxidation

14.

The table shows how metals in different positions in the reactivity series are extracted (from the source material).

Reactivity	Metals	Method of extraction
Above carbon	Aluminium	Electrolysis of molten compounds
Below carbon	Iron, Zinc	Heating with carbon or carbon monoxide
Very unreactive	Copper	Found native or needs little processing

Which of the following is correctly matched with its extraction method?

Medium

AAluminium - electrolysis
BIron - electrolysis
CZinc - electrolysis
DCopper - reduction with carbon

15.A student is given a sample of an unknown metal ore. The ore is heated strongly with carbon and a metal is produced. Which metal could NOT be extracted by this method?
Medium
- AAluminium
- BZinc
- CIron
- DCopper
16.In the blast furnace, what is the purpose of adding limestone (calcium carbonate)?
Easy
- ATo remove impurities such as silicon dioxide
- BTo provide heat by burning
- CTo reduce iron(III) oxide to iron
- DTo increase the concentration of iron ore
17.During the electrolysis of aluminium oxide dissolved in molten cryolite, the reaction at the cathode is Al3+ + 3e- → Al. What is the correct description of this process?
Medium
- AReduction, because aluminium ions gain electrons
- BOxidation, because aluminium ions gain electrons
- CReduction, because aluminium ions lose electrons
- DOxidation, because aluminium ions lose electrons
18.How does increasing the carbon content of iron produced in the blast furnace affect its malleability?
Medium
- AMalleability decreases as carbon content increases
- BMalleability increases as carbon content increases
- CMalleability is highest at around 2% carbon
- DMalleability is unaffected by carbon content
19.Which of the following is the main ore of iron?
Easy
- AHematite
- BBauxite
- CMalachite
- DLimestone
20.In the laboratory, a student wants to obtain a sample of copper metal from malachite (copper carbonate). Which of the following sequences of steps is correct?
Medium
- ACrush the malachite, heat it strongly, then reduce the copper oxide with carbon.
- BDissolve the malachite in water, then electrolyze the solution.
- CHeat the malachite with carbon directly to obtain copper.
- DAdd acid to the malachite, then add zinc to displace copper.
21.Which of the following reactions in the blast furnace is an example of thermal decomposition?
Easy
- AC + O2 → CO2
- BCO2 + C → 2CO
- CCaCO3 → CaO + CO2
- DFe2O3 + 3CO → 2Fe + 3CO2
22.In the extraction of iron, the reaction Fe2O3 + 3CO → 2Fe + 3CO2 shows that iron(III) oxide is reduced. What is the reducing agent?
Easy
- AIron(III) oxide
- BCarbon monoxide
- CIron
- DCarbon dioxide
23.Which statement about the extraction of metals is correct?
Medium
- AMetals above carbon in the reactivity series are extracted by reduction with carbon.
- BMetals below carbon in the reactivity series are extracted by electrolysis.
- CMetals above carbon in the reactivity series are extracted by electrolysis.
- DAll metals are extracted by reduction with carbon.
24.During the electrolysis of aluminium oxide, what is produced at the positive electrode (anode)?
Easy
- Aaluminium
- Boxygen
- Ccarbon dioxide
- Dcryolite
25.Which of the following is a raw material added to the blast furnace for iron extraction?
Easy
- Ahematite
- Bcryolite
- Cbauxite
- Dsodium chloride
26.In the extraction of iron, what is the name of the molten waste product formed from impurities?
Easy
- Aslag
- Bcoke
- Cflux
- Dgangue
27.Which of the following statements about the extraction of aluminium is correct?
Medium
- AAluminium is extracted by reduction with carbon because it is below carbon in the reactivity series.
- BThe overall reaction is 2Al₂O₃ → 4Al + 3O₂, and the carbon anodes are consumed because oxygen reacts with them.
- CCryolite is added to increase the melting point of the mixture.
- DAluminium is produced at the positive electrode (anode).
28.In the blast furnace, the reaction CaCO3 → CaO + CO2 occurs. What is the purpose of this reaction?
Medium
- ATo provide heat for the furnace
- BTo produce calcium oxide which removes impurities
- CTo produce carbon dioxide which reduces iron oxide
- DTo produce carbon monoxide which reduces iron oxide
29.A blast furnace produces 10,000 tonnes of iron per day. If the iron ore (hematite, Fe2O3) is 70% pure, what mass of ore is needed per day to produce this amount of iron? (Ar: Fe=56, O=16)
Hard
- A14,286 tonnes
- B20,408 tonnes
- C24,490 tonnes
- D28,571 tonnes
30.The extraction of a metal from its oxide ore is an oxidation process.
Easy
True or false?
31.Complete the sentence.
Easy
A metal ore is a rock that contains enough of the metal to make it ____ extracting.
32.Name the three raw materials added to the top of the blast furnace.
Easy
The three raw materials added to the top of the blast furnace are ____, ____, and ____.
33.Complete the half-equation at the cathode during the electrolysis of aluminium oxide.
Medium
At the cathode: ____ + 3e⁻ → ____
34.State what is meant by the term 'native metal'.
Easy
35.In the blast furnace, limestone is added to remove silicon dioxide impurities by forming calcium silicate (slag).
Easy
True or false?
36.In the blast furnace, the reaction C + CO₂ → 2CO is an example of reduction.
Medium
True or false?
37.Match each raw material in the blast furnace to its role.
Easy
- Iron ore (hematite)
- Coke
- Limestone
- Provides iron(III) oxide
- Provides carbon and heat
- Removes impurities
38.Match each raw material in the blast furnace to its correct role.
Easy
- Iron ore (hematite)
- Coke
- Limestone
- Provides iron(III) oxide
- Produces reducing agent and heat
- Removes impurities as slag
39.Arrange the following steps in the correct order for the extraction of iron in the blast furnace.
Medium
- Coke burns to form CO2
- CO reduces Fe2O3 to Fe
- C + CO2 → 2CO
- Limestone decomposes to CaO and CO2
40.Which of the following statements about the extraction of aluminium are correct? (Select all that apply.)
Hard
- AAluminium is extracted by electrolysis of molten aluminium oxide.
- BAluminium oxide is dissolved in molten cryolite to lower the melting point.
- CThe cathode is made of graphite and is consumed during the process.
- DOxygen gas is produced at the anode.
- EThe overall reaction is 2Al2O3 → 4Al + 3O2.
41.Use industrial datasets to compare the energy inputs of alternative extraction routes for a specified metal. What is the independent variable?
Easy
- Aenergy used per kilogram of metal produced
- Bthe number of repeated trials
- Cthe scientific explanation written afterwards
- Dthe extraction route
42.Use industrial datasets to compare the energy inputs of alternative extraction routes for a specified metal. Which observation or quantity is the dependent variable?
Easy
- Aenergy used per kilogram of metal produced
- Bthe extraction route
- Cthe title given to the investigation
- Dthe number of references in the report
43.Use industrial datasets to compare the energy inputs of alternative extraction routes for a specified metal. Which decision best controls another factor in this comparison?
Medium
- Achange every condition for each trial
- Bcompare the same metal and the same product purity
- Cuse a different measurement method for every result
- Drecord only results that agree with the prediction
44.Use industrial datasets to compare the energy inputs of alternative extraction routes for a specified metal. Why should the class repeat measurements or check multiple comparable observations?
Medium
- ATo guarantee that every systematic error disappears
- BTo make an unsupported prediction become correct
- CTo assess variation and judge how consistent the evidence is
- DTo avoid reporting results that disagree with a model
45.A class is evaluating an application of metal extraction and resource choices. Which statement identifies a relevant limitation?
Hard
- AAll scientific models reproduce every feature of the real world
- BOne favourable result proves that a technology has no disadvantages
- CA conclusion needs no evidence when a scientific term is used
- DCompare collection, transport, sorting, purity and energy together; one energy figure is not a complete environmental assessment.
46.Use industrial datasets to compare the energy inputs of alternative extraction routes for a specified metal. Which conclusion is most justified by a controlled comparison?
Hard
- AA conclusion restricted to the tested conditions, with uncertainty and limitations stated
- BA claim that the result must hold in all possible conditions
- CA claim that alternative explanations never need testing
- DA claim based only on the most convenient observation
47.Use industrial datasets to compare the energy inputs of alternative extraction routes for a specified metal. Select the two practices that strengthen the validity of this comparison.
Medium
- Acompare the same metal and the same product purity
- Bchange the measurement method whenever a result is unexpected
- Crecord energy used per kilogram of metal produced using the same agreed procedure
- Dreport only observations that confirm the prediction
48.When evaluating evidence about metal extraction and resource choices, select the two scientifically defensible statements.
Hard
- AOne result proves the explanation in every situation
- BCompare collection, transport, sorting, purity and energy together; one energy figure is not a complete environmental assessment.
- CA conclusion should state the conditions and uncertainty of the evidence
- DModels never need revision when new evidence appears
49.Design a fair investigation for this question: Use industrial datasets to compare the energy inputs of alternative extraction routes for a specified metal. Identify what to compare, what to record and one control.
Medium
50.Explain one use of the science in metal extraction and resource choices and evaluate one limitation of the evidence or application.
Hard
51.Why is aluminium oxide usually electrolysed rather than reduced with carbon to extract aluminium?
Hard
- AAluminium oxide contains no ions
- BAluminium is more reactive than carbon, so carbon does not readily remove its oxygen
- CAll metals can only be extracted by electrolysis
- DAluminium is less reactive than copper
52.A classroom dataset gives 180 MJ/kg for a primary-metal route and 12 MJ/kg for recycling. What is the calculated energy saving per kilogram within those stated boundaries?
Hard
- A192 MJ/kg
- B15 MJ/kg
- C168 MJ/kg
- D0.067 MJ/kg

Revision notes

## Big idea: metal extraction and resource choices - **Key concept: Systems.** Metals below carbon in the reactivity series can often be extracted by reduction with carbon. More reactive metals such as aluminium require electrolysis of suitable compounds. - **Related concepts: Models and evidence.** Use a scientific explanation to make predictions, then test it against observations. - **Global context: Scientific and technical innovation.** Recycling can reduce demand for fresh ore and extraction energy. ## Metals and Ores - The Earth’s crust contains metals and metal compounds. - A **metal ore** is a rock that contains enough of the metal to make extraction worthwhile. - Many metal ores are **oxides** (e.g., hematite for iron, bauxite for aluminium). - Extraction is a **reduction** process because oxygen is removed from the ore. - Very unreactive metals like **gold** and **platinum** are found **native** (as uncombined elements). ## Reactivity Series and Extraction Method - The extraction method depends on the metal's position in the **reactivity series**. - Metals **above carbon** must be extracted by **electrolysis** (e.g., aluminium). - Metals **below carbon** can be extracted by heating with **carbon** or **carbon monoxide** (e.g., iron). - Metals lower in the series are easier to extract than those higher up. - Electrolysis uses large amounts of electricity, making it expensive. ## Extraction of Iron from Hematite – Blast Furnace - Iron is extracted from its ore **hematite** (Fe₂O₃) in a **blast furnace**. - Raw materials: iron ore, **coke** (impure carbon), and **limestone** (CaCO₃). - Hot air is blown into the bottom of the furnace. ## Reactions in the Blast Furnace - **Zone 1:** Coke burns: C + O₂ → CO₂ (exothermic, provides heat). - **Zone 2:** CO₂ + C → 2CO (carbon monoxide is the main reducing agent). - **Zone 3:** Fe₂O₃ + 3CO → 2Fe + 3CO₂ (reduction of iron ore). - Limestone decomposes: CaCO₃ → CaO + CO₂ (thermal decomposition). - CaO removes SiO₂ impurity: CaO + SiO₂ → CaSiO₃ (slag). - Molten iron is tapped from the bottom; slag floats on top and is removed separately. ## Extraction of Aluminium from Bauxite – Electrolysis - Aluminium is extracted from **bauxite** (Al₂O₃) by **electrolysis**. - Aluminium is above carbon in the reactivity series, so carbon reduction is not possible. - Al₂O₃ is dissolved in molten **cryolite** to lower the melting point (from >2000°C to ~950°C). - The electrolysis cell has a **graphite** lining (cathode) and graphite anodes. - At cathode: Al³⁺ + 3e⁻ → Al (reduction). - At anode: 2O²⁻ → O₂ + 4e⁻ (oxidation). - Overall: 2Al₂O₃ → 4Al + 3O₂. - Oxygen reacts with the carbon anodes to form CO₂, so anodes wear away and must be replaced. ## Explaining and applying the science - Remember OIL RIG: **O**xidation **I**s **L**oss (of electrons), **R**eduction **I**s **G**ain (of electrons). - For iron extraction, know the three zones and the role of limestone. - For aluminium, explain why cryolite is used and why anodes need replacing. - Unreactive metals (Cu, Ag, Au) may be found native or extracted by simple heating. ## Think like a scientist - Use industrial datasets to compare the energy inputs of alternative extraction routes for a specified metal. - **Comparison:** the extraction route. **Outcome:** energy used per kilogram of metal produced. - **Control:** compare the same metal and the same product purity. Explain why this makes the comparison fairer. - **Evidence:** Use a consistent method, repeated observations where appropriate and a table with labelled quantities and units. Keep unexpected results and investigate their cause. - **Safety:** Practical activities need teacher supervision and an appropriate risk assessment. Use the provided data or simulation where the investigation specifies it. - **Inquiry task:** State a testable question, predict the outcome using the science, then explain how your observations would support or challenge the prediction. ## Evaluate the science - Recycling can reduce demand for fresh ore and extraction energy. - Compare collection, transport, sorting, purity and energy together; one energy figure is not a complete environmental assessment. - **Evaluation task:** Link your conclusion to evidence, identify a limitation and suggest a specific improvement. Distinguish a measured result from an explanation of its cause.

Describing Aluminium Electrolysis: Describe the electrolysis of molten aluminium oxide (bauxite) including the use of cryolite, electrode reactions, and overall equation.
Describing Blast Furnace Process: Describe the extraction of iron from hematite in the blast furnace, including the roles of coke, limestone, and the chemical reactions.
Relating Reactivity to Extraction Method: Determine the extraction method (electrolysis, reduction with carbon, or native) based on a metal's position in the reactivity series.
Writing Equations for Iron Extraction: Write balanced chemical equations for the reactions in the blast furnace (combustion, formation of CO, reduction of Fe2O3, decomposition of limestone, slag formation).
Explaining Electrode Reactions: Identify oxidation and reduction at the electrodes during aluminium extraction and write half-equations.
Designing scientific inquiries: Plan a fair comparison: Use industrial datasets to compare the energy inputs of alternative extraction routes for a specified metal.
Evaluating evidence and impacts: Recycling can reduce demand for fresh ore and extraction energy. Compare collection, transport, sorting, purity and energy together; one energy figure is not a complete environmental assessment.
Metals and Ores: The Earth’s crust contains metals and metal compounds.
Reactivity Series and Extraction Method: The extraction method depends on the metal's position in the **reactivity series**.
Extraction of Iron from Hematite – Blast Furnace: Iron is extracted from its ore **hematite** (Fe₂O₃) in a **blast furnace**.
Reactions in the Blast Furnace: **Zone 1:** Coke burns: C + O₂ → CO₂ (exothermic, provides heat).
Extraction of Aluminium from Bauxite – Electrolysis: Aluminium is extracted from **bauxite** (Al₂O₃) by **electrolysis**.
Explaining and applying the science: Remember OIL RIG: **O**xidation **I**s **L**oss (of electrons), **R**eduction **I**s **G**ain (of electrons).
metal ore: A **metal ore** is a rock that contains enough of the metal to make extraction worthwhile.
oxides: Many metal ores are **oxides** (e.g., hematite for iron, bauxite for aluminium).
reduction: Extraction is a **reduction** process because oxygen is removed from the ore.

Flashcards

Which of the following is the main ore of aluminium?

Bauxite The main ore of aluminium is bauxite, which contains aluminium oxide.

Which of the following metals is found native (as the uncombined element) in the Earth's crust?

Gold Very unreactive metals such as gold and platinum are found native.

What is the main reducing agent in the blast furnace for the extraction of iron?

Carbon monoxide Carbon monoxide is the main reducing agent in the blast furnace.

In the extraction of aluminium by electrolysis, why is aluminium oxide dissolved in molten cryolite?

To lower the melting point of the mixture Aluminium oxide has a melting point over 2000°C, so it is dissolved in molten cryolite to lower the melting point and reduce energy costs.

In the blast furnace, which substance is added to remove impurities such as silicon dioxide?

Limestone Limestone (calcium carbonate) is added to remove impurities; it decomposes to calcium oxide which reacts with silicon dioxide to form slag.

Which of the following statements about transition elements is correct?

Their compounds are highly coloured Transition elements have highly coloured compounds and often have more than one oxidation state.

The overall equation for the extraction of aluminium is 2Al2O3 → 4Al + 3O2. At the anode, oxygen reacts with the graphite electrodes. What is the main reason the anodes need to be replaced periodically?

The graphite reacts with oxygen to form CO2, wearing away the anode The carbon in the graphite anodes reacts with the oxygen produced to form CO2, causing the anode to wear away and need replacement.

In the blast furnace, which reaction is an example of thermal decomposition?

CaCO3 → CaO + CO2 The thermal decomposition of calcium carbonate (limestone) to calcium oxide and carbon dioxide is an example of thermal decomposition.

Which of the following metals is extracted by reduction with carbon?

Iron Metals below carbon in the reactivity series, such as iron, can be extracted by heating with carbon or carbon monoxide.

Why is aluminium not extracted by reduction with carbon?

Aluminium is above carbon in the reactivity series Aluminium is higher in the reactivity series than carbon, so it cannot be extracted by reduction using carbon; it must be extracted by electrolysis.

In the electrolysis of aluminium oxide, what is produced at the negative electrode (cathode)?

Aluminium At the cathode, aluminium ions gain electrons to form molten aluminium.

In the blast furnace, the reaction Fe2O3 + 3CO → 2Fe + 3CO2 shows that iron(III) oxide is reduced. What is the reducing agent?

Carbon monoxide Carbon monoxide reduces iron(III) oxide to iron; the reducing agent is the species that causes reduction by removing oxygen, which is carbon monoxide.

In a blast furnace, the reaction CaCO3 → CaO + CO2 occurs. Which type of reaction is this?

Thermal decomposition The reaction involves breaking down calcium carbonate by heat, which is thermal decomposition.

The table shows how metals in different positions in the reactivity series are extracted (from the source material). | Reactivity | Metals | Method of extraction | |---|---|---| | Above carbon | Aluminium | Electrolysis of molten compounds | | Below carbon | Iron, Zinc | Heating with carbon or carbon monoxide | | Very unreactive | Copper | Found native or needs little processing | Which of the following is correctly matched with its extraction method?

Aluminium - electrolysis The table shows aluminium is above carbon, so it needs electrolysis. Iron and zinc are below carbon, so they are extracted by heating with carbon/carbon monoxide, not electrolysis. Copper is very unreactive and is found native, not extracted by carbon reduction. Only 'Aluminium - electrolysis' correctly matches a metal with its method.

A student is given a sample of an unknown metal ore. The ore is heated strongly with carbon and a metal is produced. Which metal could NOT be extracted by this method?

Aluminium Aluminium is above carbon in the reactivity series and cannot be reduced by carbon; it requires electrolysis. Zinc, iron, and copper are below carbon and can be extracted by reduction with carbon.

In the blast furnace, what is the purpose of adding limestone (calcium carbonate)?

To remove impurities such as silicon dioxide Limestone decomposes to CaO, which reacts with SiO2 impurity to form calcium silicate (slag), which is removed.

How would you design the inquiry for metal extraction and resource choices?

Use industrial datasets to compare the energy inputs of alternative extraction routes for a specified metal. Compare the extraction route; record energy used per kilogram of metal produced; compare the same metal and the same product purity.

What limitation matters when applying metal extraction and resource choices?

Compare collection, transport, sorting, purity and energy together; one energy figure is not a complete environmental assessment.

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