Extraction Of Metals

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Metals and Ores

The Earth’s crust contains metals and metal compounds.
A metal ore is a rock containing enough metal to make extraction worthwhile.
Many metal ores are oxides (e.g., hematite – iron ore, bauxite – aluminium ore).
Extraction involves removing oxygen from the compound, so it is a reduction process.
Very unreactive metals like gold and platinum occur native (uncombined).

Reactivity Series and Extraction Method

The higher a metal in the reactivity series, the harder it is to extract.
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 in blast furnace).
Very unreactive metals (e.g., gold, silver) are often found native or require little processing.

Extraction of Iron from Hematite – The Blast Furnace

Iron is extracted in a blast furnace from its ore hematite (Fe₂O₃).
Raw materials: iron ore, coke (impure carbon), and limestone are added at the top.
Hot air is blown into the bottom.
Zone 1: Coke burns in hot air to form CO₂, providing heat: C + O₂ → CO₂.
Zone 2: Coke reacts with CO₂ to form CO (main reducing agent): C + CO₂ → 2CO.
Zone 3: CO reduces iron(III) oxide to molten iron: Fe₂O₃ + 3CO → 2Fe + 3CO₂.
Limestone decomposes to CaO, which reacts with SiO₂ impurity to form slag (calcium silicate).
Molten iron and slag are tapped off separately.

The blast furnace

Extraction of Aluminium from Bauxite – Electrolysis

Aluminium is above carbon in the reactivity series, so it cannot be reduced by carbon.
Its ore is bauxite (aluminium oxide, Al₂O₃).
Aluminium oxide is dissolved in molten cryolite to lower the melting point.
The mixture is electrolysed using carbon electrodes.
Aluminium ions are reduced at the cathode to form molten aluminium metal.
Oxide ions are oxidised at the anode to form oxygen gas.
The carbon anodes are burned away by the oxygen and must be replaced regularly.

Electrolysis of aluminium oxide

Key Equations (Extended Tier)

Burning of coke: C(s) + O₂(g) → CO₂(g)
Formation of CO: CO₂(g) + C(s) → 2CO(g)
Reduction of iron ore: Fe₂O₃(s) + 3CO(g) → 2Fe(l) + 3CO₂(g)
Thermal decomposition of limestone: CaCO₃(s) → CaO(s) + CO₂(g)
Slag formation: CaO(s) + SiO₂(s) → CaSiO₃(l)

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Übungsfragen

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1.What is a metal ore?
Easy
- AA rock that contains enough of a metal to make extraction worthwhile
- BA pure metal found in the Earth's crust
- CA compound of a metal with oxygen only
- DA mineral that contains carbon
2.Extraction of a metal from its ore is a reduction process because oxygen is removed from the compound.
Easy
True or false?
3.Which metal is found native (uncombined) in the Earth's crust?
Easy
- AIron
- BAluminium
- CGold
- DZinc
4.Complete the sentence about the extraction of iron.
Easy
In the blast furnace, the main reducing agent is ____.
5.State two raw materials added to the top of the blast furnace for iron extraction.
Medium
6.How many tonnes of iron does a modern blast furnace produce per day?
Easy
- A9000
- B10000
- C12000
- D11000
7.Why is aluminium extracted by electrolysis rather than by heating with carbon?
Medium
- AAluminium is more reactive than carbon
- BAluminium is less reactive than carbon
- CAluminium ore is not an oxide
- DAluminium has a low melting point
8.What is the purpose of adding limestone to the blast furnace?
Easy

Mehr Fragen

9.Match each metal to its extraction method.
Medium
- Potassium
- Zinc
- Copper
- Electrolysis
- Heating with carbon
- Found native
10.Arrange the following metals in order of increasing difficulty of extraction (easiest first).
Medium
- Iron
- Aluminium
- Gold
11.In the blast furnace, carbon burns to form carbon dioxide. If 12 g of carbon burns completely, what mass of carbon dioxide is produced? (Ar: C=12, O=16)
Medium
- A52
- B44
- C40
- D48
12.In the extraction of aluminium, aluminium oxide is dissolved in molten cryolite to lower the melting point and save energy.
Easy
True or false?
13.Gold is found native in the Earth's crust because it is very unreactive.
Easy
True or false?
14.Which of the following metals is extracted by electrolysis?
Easy
- AIron
- BCopper
- CAluminium
- DZinc
15.In the extraction of aluminium, aluminium oxide is dissolved in molten cryolite to increase the melting point.
Easy
True or false?
16.What is the purpose of adding limestone to the blast furnace during iron extraction?
Medium
- ATo provide carbon monoxide
- BTo remove impurities (silicon dioxide)
- CTo increase the temperature
- DTo reduce iron(III) oxide
17.Arrange the following metals in order of increasing ease of extraction (easiest first).
Medium
- Iron
- Aluminium
- Gold
- Zinc
18.Which equation represents the reduction of iron(III) oxide in the blast furnace?
Medium
- AFe2O3 + 3C → 2Fe + 3CO
- BFe2O3 + 3CO → 2Fe + 3CO2
- C2Fe2O3 + 3C → 4Fe + 3CO2
- DFe2O3 + CO → 2Fe + CO2
19.Extraction of a metal from its ore is an oxidation process because oxygen is added.
Easy
True or false?
20.Which of the following are native metals? (Select all that apply)
Medium
- AGold
- BIron
- CPlatinum
- DAluminium
- ECopper
21.Which of the following are extracted by electrolysis? (Select all that apply)
Medium
- AAluminium
- BIron
- CZinc
- DSodium
- EGold
22.In the blast furnace, carbon monoxide reduces iron(III) oxide to iron.
Medium
True or false?
23.Which of the following metals is found native in the Earth's crust?
Easy
- AGold
- BIron
- CAluminium
- DZinc
24.Which of the following equations represent reactions that occur in the blast furnace? (Select all that apply)
Hard
- AC + O2 → CO2
- BCO2 + C → 2CO
- CFe2O3 + 3CO → 2Fe + 3CO2
- DCaCO3 → CaO + CO2
- E2Al2O3 → 4Al + 3O2
25.Put the following steps in the blast furnace in order from first to last.
Medium
- Coke burns to form carbon dioxide
- Carbon monoxide reduces iron(III) oxide to iron
- Carbon dioxide reacts with coke to form carbon monoxide
- Limestone decomposes to calcium oxide
26.A company wants to extract a metal from its ore. The metal is above carbon in the reactivity series. Which extraction method should be used?
Easy
- AElectrolysis
- BHeating with carbon monoxide
- CHeating with carbon
- DPhysical separation
27.Which of the following are raw materials added to the top of a blast furnace for iron extraction? (Select all that apply)
Medium
- AIron ore (hematite)
- BCoke
- CLimestone
- DHot air
- ECarbon monoxide
28.Aluminium is extracted from its ore by heating with carbon.
Easy
True or false?
29.Which of the following metals is likely to be found native (uncombined) in the Earth's crust?
Easy
- AGold
- BIron
- CAluminium
- DZinc
30.In the blast furnace, what is the main reducing agent that converts iron(III) oxide to iron?
Easy
- ACarbon (coke)
- BCarbon monoxide
- CCarbon dioxide
- DCalcium oxide
31.A metal that is found native in the Earth's crust is likely to be very reactive.
Easy
True or false?
32.In the blast furnace, what is the purpose of adding limestone?
Medium
- ATo provide a source of carbon monoxide
- BTo remove impurities by forming slag
- CTo increase the temperature of the furnace
- DTo reduce iron(III) oxide to iron
33.Which of the following equations represents the reduction of iron(III) oxide in the blast furnace?
Medium
- AFe₂O₃ + 3CO → 2Fe + 3CO₂
- BFe₂O₃ + 3C → 2Fe + 3CO
- CFe₂O₃ + 3CO₂ → 2Fe + 3CO
- DFe₂O₃ + 2CO → 2Fe + 2CO₂
34.Which of the following metals is extracted by heating with carbon or carbon monoxide?
Easy
- AAluminium
- BPotassium
- CIron
- DGold
35.Which of the following metals is found native (uncombined) in the Earth's crust?
Easy
- AIron
- BSodium
- CGold
- DZinc
36.In the blast furnace, the main reducing agent that converts iron(III) oxide to iron is carbon monoxide.
Easy
True or false?
37.A company is extracting a metal from its ore by heating with carbon. Which metal is most likely being extracted?
Easy
- AAluminium
- BIron
- CPotassium
- DGold
38.In the blast furnace, which substance is the main reducing agent that converts iron(III) oxide to iron?
Easy
- ACarbon (coke)
- BCarbon dioxide
- CCarbon monoxide
- DLimestone
39.During the extraction of aluminium, aluminium oxide is dissolved in molten cryolite. What is the main reason for using cryolite?
Medium
- ATo lower the melting point of the mixture
- BTo increase the conductivity of the electrolyte
- CTo prevent the aluminium from reacting with air
- DTo provide a source of aluminium ions
40.Which of the following metals are found native (uncombined) in the Earth's crust? (Select all that apply)
Medium
- AGold
- BIron
- CPlatinum
- DAluminium
- ESodium
41.Place the following steps in the blast furnace in the correct order from first to last.
Medium
- Carbon monoxide reduces iron(III) oxide to iron
- Coke burns in hot air to form carbon dioxide
- Carbon dioxide reacts with more coke to form carbon monoxide
- Molten iron is tapped off from the bottom
42.In an experiment to extract iron from its ore, a student heats a mixture of iron(III) oxide and carbon powder. Which gas is produced as a result of the reduction reaction?
Medium
- ACarbon dioxide
- BCarbon monoxide
- COxygen
- DHydrogen
43.A student is testing a metal ore to determine if it contains a metal that can be extracted by heating with carbon. Which property of the metal is most important to consider?
Medium
- AIts density
- BIts reactivity compared to carbon
- CIts melting point
- DIts electrical conductivity
44.Complete the sentence about extraction of iron.
Easy
In the blast furnace, the main reducing agent is ____.
45.State one raw material added to the top of the blast furnace for iron extraction.
Easy
46.Complete the sentences about the extraction of aluminium.
Medium
Aluminium is extracted by ____ . Aluminium oxide is dissolved in molten ____ to lower the melting point.
47.In the blast furnace, carbon monoxide reduces iron(III) oxide. Calculate the mass of iron produced when 160 g of iron(III) oxide is completely reduced by excess carbon monoxide. (Ar: Fe=56, O=16)
Hard
48.In the blast furnace, iron(III) oxide is reduced by carbon monoxide. Calculate the mass of iron produced when 320 g of iron(III) oxide (Fe₂O₃) is completely reduced. (Ar: Fe=56, O=16)
Hard
49.State one reason why cryolite is used in the extraction of aluminium.
Easy
50.A blast furnace produces 10,000 tonnes of iron per day. If the furnace operates 365 days a year, how many tonnes of iron does it produce in one year?
Easy
51.Complete the sentence.
Easy
A metal ore is a rock that contains enough of the ____ to make it worthwhile extracting.
52.Complete the sentences about the blast furnace.
Easy
In zone 1, carbon burns to form ____. In zone 2, carbon reacts with carbon dioxide to form ____, which is the main reducing agent.
53.Explain why aluminium is extracted by electrolysis rather than by heating with carbon.
Medium
54.Explain why limestone is added to the blast furnace during iron extraction.
Medium
55.Explain why limestone is added to the blast furnace during iron extraction. Include the relevant chemical equations.
Medium
56.Explain why aluminium is extracted by electrolysis rather than by heating with carbon. Include the relevant position in the reactivity series.
Medium
57.In the blast furnace, carbon monoxide reduces iron(III) oxide. Calculate the mass of iron produced when 160 g of iron(III) oxide is completely reduced by excess carbon monoxide. (Ar: Fe=56, O=16)
Hard
- A112 g
- B101 g
- C123 g
- D134 g
58.In the blast furnace, iron(III) oxide is reduced by carbon monoxide. Calculate the mass of iron produced when 320 g of iron(III) oxide (Fe₂O₃) is completely reduced. (Ar: Fe=56, O=16)
Hard
- A268 g
- B246 g
- C224 g
- D202 g
59.A blast furnace produces 10,000 tonnes of iron per day. If the furnace operates 365 days a year, how many tonnes of iron does it produce in one year?
Easy
- A3285000 tonnes
- B4015000 tonnes
- C3650000 tonnes
- D4380000 tonnes

Karteikarten

What is a metal ore?

A rock that contains enough of the metal to make it worthwhile extracting.

Why is the extraction of a metal from its oxide ore a reduction process?

Because oxygen is removed from the metal compound.

What are native metals? Give two examples.

Very unreactive metals found as uncombined elements. Examples: gold and platinum.

How does the position of a metal in the reactivity series affect its extraction method?

Metals above carbon must be extracted by electrolysis; metals below carbon can be extracted by heating with carbon or carbon monoxide.

Which metal is commonly extracted by electrolysis?

Aluminium.

Which metal is commonly extracted in a blast furnace?

Iron.

What are the raw materials added to the top of a blast furnace?

Iron ore (hematite), coke (impure carbon), and limestone.

What is the purpose of hot air blown into the bottom of a blast furnace?

To burn coke, producing heat and carbon dioxide.

Write the equation for the burning of coke in the blast furnace.

C + O2 → CO2

What is the main reducing agent in the blast furnace?

Carbon monoxide (CO).

Write the equation for the formation of carbon monoxide in the blast furnace.

CO2 + C → 2CO

Write the equation for the reduction of iron(III) oxide by carbon monoxide.

Fe2O3 + 3CO → 2Fe + 3CO2

What is the purpose of limestone in the blast furnace?

To remove impurities (silicon dioxide) from the iron ore.

Write the equation for the thermal decomposition of limestone.

CaCO3 → CaO + CO2

Write the equation for the formation of slag in the blast furnace.

CaO + SiO2 → CaSiO3

What is slag and how is it removed?

Molten calcium silicate that floats on top of molten iron and is tapped off separately.

Why is aluminium not extracted by reduction with carbon?

Because aluminium is more reactive than carbon, so carbon cannot reduce aluminium oxide.

How is aluminium extracted from its ore?

By electrolysis of aluminium oxide dissolved in molten cryolite.

What is the ore of aluminium called?

Bauxite (contains aluminium oxide).

Why is cryolite used in aluminium extraction?

To lower the melting point of aluminium oxide, making electrolysis more economical.

What is produced at the cathode during aluminium electrolysis?

Molten aluminium metal.

What is produced at the anode during aluminium electrolysis?

Oxygen gas (which reacts with the carbon anode to form CO2).

Why is electrolysis an expensive method of extraction?

It requires a large amount of electricity.

Which metals are often found native?

Very unreactive metals such as gold and platinum.

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