IGCSEChemistry: Co-ordinated Sciences (Double Award)CIEExam QuestionsMetalsExtraction of Metals

Extraction of Metals (CIE IGCSE Chemistry: Co-ordinated Sciences (Double Award))

Exam Questions

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Extraction of Metals

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Extraction of Metals

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1a3 marks

Iron is a transition element.

Which of the following statements about transition elements are correct?

Tick three boxes.

The metals are highly coloured e.g. yellow, green, blue.  
The metals have low melting points.  
Their compounds are highly coloured.  
Their compounds are colourless.  
The elements and their compounds are often used as catalysts.  
They have more than one oxidation state.  

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1b2 marks
i)




In which Period in the Periodic Table is iron to be found?
[1]
ii)
Use the Periodic Table to work out the number of protons and the number of neutrons in one atom of iron.

Number of protons =

Number of neutrons = 

[1]

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1c3 marks

Iron is extracted in a blast furnace. The list below gives some of the substances used or formed in the extraction.

carbon monoxide coke iron ore limestone slag

i)
Which substance is a mineral containing largely calcium carbonate?

[1]

ii)
Which substance is formed when impurities in the ore react with calcium oxide?

[1]

iii)
Which substance is also called hematite?

[1]

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1d2 marks

State two functions of the coke used in the blast furnace.

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1e1 mark

Some of the iron is converted into stainless steel. Give one use for stainless steel.

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2a5 marks

Extended tier only

The diagram shows a blast furnace.

screen-shot-2022-09-14-at-08-25-23

The following equations represent reactions which take place in the blast furnace.

   A    C + O2 → CO2
   B    CaCO3 → CaO + CO2
   C    CaO + SiO2 → CaSiO3
   D    CO2 + C → 2CO
   E    Fe2O3 + 3CO → 2Fe + 3CO2

i)
Which reaction is used to increase the temperature inside the blast furnace?
[1]
ii)
Which reaction is an example of thermal decomposition?
[1]
iii)
In which reaction is carbon both oxidised and reduced?
[1]
iv)
Which equation shows the removal of an impurity from the iron? 
[1]
v)
Which equation shows the reaction of an acidic substance with a basic substance?
[1]

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2b4 marks

Use the diagram of the blast furnace to help you answer these questions.

i)
What enters the blast furnace at X?

[1]

ii)
What leaves the blast furnace at Y?

[1]

iii)
Name two waste gases that leave the blast furnace.

1. .........................................................................................................................................

2. .........................................................................................................................................

[2]

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2c3 marks

Extended tier only

The graph shows how the malleability of iron changes as the percentage of carbon in the iron changes.

screen-shot-2022-09-14-at-10-02-27

i)
Describe how the malleability of iron changes as the percentage of carbon changes.
[1] 
ii)
Iron obtained from the blast furnace contains high levels of carbon. Explain how the amount of carbon in the iron can be decreased.
[2]

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3a3 marks

Extended tier only

Aluminium reacts very slowly with aqueous copper(II) sulphate.

2Al (s) + 3CuSO4 (aq) → Al2(SO4)3 (aq) + 3Cu (s)

i)
Which of the two metals has the greater tendency to form ions?

[1]

ii)
Describe what you would see when this reaction occurs.

[1]

iii)
Explain why aluminium reacts so slowly.

[1]

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3b2 marks

Extended tier only.

Complete the following table by writing “reaction” or “no reaction” in the spaces provided.

Oxide Type of oxide Reaction with acid Reaction with alkali
magnesium basic  .................................. ..................................
aluminium amphoteric  .................................. ..................................

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4a1 mark

Aluminium is extracted by electrolysis. Iron is extracted from its ore by reduction with carbon.

Name the main ore of aluminium.

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4b1 mark

Explain why aluminium cannot be extracted by reduction with carbon.

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5a1 mark

This question is about iron and iron compounds.

Name the main ore of iron.

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5b2 marks

In a blast furnace used for the extraction of iron, carbon reacts with oxygen from the air to form carbon monoxide.

Complete the chemical equation for this reaction.

 
.....C + ..... → 2CO

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5c1 mark

In the hotter parts of the furnace, carbon reacts with the iron(III) oxide present in the iron ore.

 
3C + Fe2O3 → 3CO + 2Fe
 

How does this equation show that carbon is oxidised?

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5d1 mark

Limestone is added to the blast furnace. The limestone is converted into calcium oxide and carbon dioxide. The reaction is endothermic.

 
CaCO3 rightwards arrow with heat on top CaO + CO2 
 

What type of chemical reaction is this?

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5e2 marks

What type of oxide is calcium oxide?

Give a reason for your answer.

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6a1 mark

This question is about iron and iron compounds.

Iron can be extracted from iron ore by reduction with carbon in a blast furnace.

Which one of these substances is an ore of iron?

Draw a circle around the correct answer.

 
bauxite         graphite         hematite          limestone
 

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6b1 mark

The equation shows one of the reactions occurring in the blast furnace.

 
2Fe2O3 + 3C → 4Fe + 3CO2
 

How does this equation show that Fe2O3 is reduced?

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6c1 mark

The carbon dioxide formed can be reduced by carbon.

 
CO2 + C rightwards arrow2CO
 

The energy level diagram for this reaction is shown.

 
q2aiii-0620_s19_qp_33
 

Explain how this diagram shows that the reaction is endothermic.

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6d1 mark

Explain why iron is extracted by reduction with carbon and not by electrolysis.

Refer to the position of iron in the reactivity series in your answer.

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1a1 mark

Aluminium was first isolated in 1827 using sodium.

AlCl3 + 3Na → Al + 3NaCl


Aluminium, obtained by this method, was more expensive than gold.

Suggest an explanation why aluminium was so expensive.

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1b2 marks

The electrolysis of a molten electrolyte is one method of extracting a metal from its ore.


Other methods are the electrolysis of an aqueous solution and the reduction of the oxide by carbon.

Explain why these last two methods cannot be used to extract aluminium.

electrolysis of an aqueous solution ...................................................................................

using carbon .....................................................................................................................

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2a4 marks

Complete the labelling of the diagram.

complete-the-diagram

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2b4 marks

Separate: Chemistry and Extended Only

The ions that are involved in the electrolysis are Al3+ and O2-.
 

i)
Write an equation for the reaction at the cathode.
[2]
ii)
Explain how carbon dioxide is formed at the anode.
[2]

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2c4 marks

Give an explanation for each of the following.
 

i)
Aluminium is used extensively in the manufacture of aircraft.
[1]
ii)
Aluminium is used to make food containers.
[2]
iii)
Aluminium electricity cables have a steel core.
[1]

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3a2 marks

Iron is extracted from its ore, hematite, in a blast furnace.

Substances added to the furnace are:

  • Iron ore, hematite, containing impurities such as silica, SiO2
  • Air
  • Coke, C
  • Limestone, CaCO3

Substances formed in the blast furnace are:

  • Molten iron
  • Molten slag
  • Waste gases such as carbon dioxide

State the two functions of the coke used in the blast furnace.

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3b2 marks

Write an equation for the conversion of hematite, Fe2O3, to iron.

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3c3 marks

Explain how the silica impurity is removed and separated from the molten iron.

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3d3 marks

The molten iron from the furnace is impure. It contains impurities which include the element carbon. Explain how the carbon is removed. Include an equation in your answer.

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4a5 marks

Iron from the Blast Furnace is impure. It contains about 5% of impurities, mainly carbon, sulfur, silicon and phosphorus, which have to be removed when this iron is converted into steel.

Explain how the addition of oxygen and calcium oxide removes these impurities. Include an equation for a reaction of oxygen and a word equation for a reaction of calcium oxide in this process.

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4b7 marks

Mild steel is the most common form of steel. Mild steel contains a maximum of 0.3% of carbon.

High carbon steel contains 2% of carbon. It is less malleable and much harder than mild steel.

i)
Give a use of mild steel.
[1]
ii)
Suggest a use of high carbon steel.

[1]

iii)
Explain why metals are malleable.
[3]
iv)
Suggest an explanation why high carbon steel is less malleable and harder than mild steel.
[2]

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5a8 marks

Iron from a blast furnace contains about 5% of the impurities – carbon, silicon, phosphorus and sulfur. Most of this impure iron is used to make steels, such as mild steel, and a very small percentage is used to make pure iron.

i)
Calcium oxide and oxygen are used to remove the impurities from the iron produced in the blast furnace.
State how these chemicals are manufactured.

calcium oxide .........................

oxygen .................................
[3] 
ii)
Describe how these two chemicals remove the four impurities. Include at least one equation in your answer.
[5] 

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5b6 marks
i)
Describe the structure of a typical metal such as iron. You may include a diagram.
[2]
ii)
Explain why pure iron is malleable.
[2]

iii)
Mild steel is an alloy of iron and carbon. Suggest why mild steel is harder than pure iron.
[2]

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6a3 marks

Iron from the blast furnace is impure. It contains 5% of impurities, mainly carbon, sulfur, silicon and phosphorus. Almost all of this impure iron is converted into the alloy, mild steel.

 
i) 
State a use of mild steel.
[1] 
ii)
Name and give a use of another iron-containing alloy.
[2] 

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6b5 marks

The oxides of carbon and sulfur are gases. The oxides of silicon and phosphorus are not.

Explain how these impurities are removed from the impure iron when it is converted into mild steel.

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7a1 mark

Iron is extracted from its ore, hematite, in the blast furnace.

screen-shot-2022-09-16-at-09-39-28

The temperature inside the blast furnace can rise to 2000 °C. Write an equation for the exothermic reaction which causes this high temperature.

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7b4 marks

Carbon monoxide is formed in the blast furnace. This reduces the ore hematite, Fe2O3, to iron.

i)
Explain how carbon monoxide is formed in the blast furnace.
[2]
ii)
Write an equation for the reduction of hematite by carbon monoxide.
[2]

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7c3 marks

Explain why it is necessary to add limestone, calcium carbonate, to the blast furnace. Include an equation in your explanation.

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7d3 marks

Extended tier only

Most of the iron from the blast furnace is converted into mild steel. A method of preventing the steel from rusting is coating it with zinc.

i)
What is the name of this method of rust prevention?
[1] 
ii)
Explain, using the idea of electron transfer, why zinc-coated steel does not rust even when the coating is scratched and the steel is in contact with oxygen and water.
[2] 

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8a2 marks

Extended tier only

No one knows where iron was first isolated. It appeared in China, the Middle East and in Africa. It was obtained by reducing iron ore with charcoal.

Complete the following equation.

Fe2O3 + ........................ → ........................ + ........................
(iron ore)   (charcoal)        

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8b3 marks

Extended tier only

In 1705 Abraham Darby showed that iron ore could be reduced using coke in a blast furnace.

screen-shot-2022-09-21-at-21-01-28

i)
The temperature in the furnace rises to 2000 °C. Write an equation for the exothermic reaction that causes this high temperature.
[1] 
ii)
In the furnace, the ore is reduced by carbon monoxide. Explain how this is formed.
[2] 

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8c2 marks

Extended tier only

The formation of slag removes an impurity in the ore.

Write a word equation for the formation of the slag.

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8d6 marks

Extended tier only

Stainless steel is an alloy of iron. It contains iron, other metals and about 0.5% of carbon.

i)
State a use of stainless steel.
[1] 
ii)
Name a metal, other than iron, in stainless steel.
[1] 
iii)
The iron from the blast furnace is impure. It contains about 5% of carbon and other impurities, such as silicon and phosphorus.
Describe how the percentage of carbon is reduced and the other impurities are removed.
[4]

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9a1 mark

A list of symbols and formulae is shown.q1a_0620-s20-qp-32_cie-igcse-chemistry

Which symbol or formula represents a compound produced by the thermal decomposition of calcium carbonate?

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9b1 mark

The diagram shows part of the structures of caesium chloride and carbon dioxide.

7H~cEP3M_q8_0620-s20-qp-32_cie-igcse-chemistry

Explain why caesium is not extracted from caesium oxide by heating with carbon.

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10a1 mark

This question is about oxides.

The names of eight substances are given.

 
aluminium oxide calcium oxide ethanol nitrogen
iron(III) oxide methane oxygen silicon(IV) oxide
 

State which substance is the main constituent of bauxite.

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10b1 mark

Give the name of the process that is used to extract aluminium from aluminium oxide.

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10c2 marks

The table shows how easy it is to reduce four metal oxides with carbon.

 
metal    oxide ease of reduction with carbon
bismuth(III) oxide reduced by carbon only above 250°C
chromium(III) oxide reduced by carbon only above 1200 °C
lead(II) oxide reduced by carbon only above 440 °C
zinc oxide reduced by carbon only above 990°C
 

Use the information in the table to put the four metals in order of their reactivity.

Put the least reactive metal first.

 q8b-0620_s19_qp_33

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1a5 marks

Zinc is extracted from an ore called zinc blende, which consists mainly of zinc sulfide, ZnS.
The zinc sulfide in the ore is first converted into zinc oxide.

Zinc oxide is converted into zinc. Zinc oxide and coke are fed into a furnace. Hot air is blown into the bottom of the furnace. The process is similar to the extraction of iron from iron oxide in a blast furnace.


Zinc has a melting point of 420 °C and a boiling point of 907 °C. The temperature inside the furnace is over 1000 °C.

 
i)
Explain how zinc oxide is converted into zinc. Your answer should include details of how the heat is produced and equations for all the reactions you describe.

[3]

ii)
Explain why the zinc produced inside the furnace is a gas.

[1]

iii)
State the name of the physical change for the conversion of gaseous zinc into molten zinc.

[1]

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1b4 marks

Extended tier only

Rusting of steel can be prevented by coating the steel with a layer of zinc.

Explain, in terms of electron transfer, why steel does not rust even if the layer of zinc is scratched so that the steel is exposed to air and water.

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2a6 marks

Extended tier only

For centuries, iron has been extracted from its ore in the blast furnace. The world production of pig iron is measured in hundreds of million tonnes annually.

The following raw materials are supplied to a modern blast furnace.

  • iron ore which is hematite, Fe2O3
  • limestone which is calcium carbonate
  • carbon in the form of coke
  • air

Describe the essential reactions in the blast furnace. Each of the four raw materials must be mentioned at least once.

Give the equation for the reduction of hematite.

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2b7 marks

Extended tier only

Each year, blast furnaces discharge millions of tonnes of carbon dioxide into the atmosphere. This will increase the percentage of atmospheric carbon dioxide.

i)
Explain why this increased percentage of carbon dioxide may cause problems in the future.

[2]

ii)
Until the early eighteenth century, charcoal, not coke, was used in the blast furnace. Charcoal is made from wood but coke is made from coal. Explain why the use of charcoal would have a smaller effect on the level of atmospheric carbon dioxide

[2]

iii)
A method being developed to produce iron with lower emissions of carbon dioxide is by electrolysis. Hematite, Fe2O3, is dissolved in molten lithium carbonate and electrolysed. The ore is spilt into its constituent elements.

Write an equation for the reaction at the negative electrode (cathode).

Complete the equation for the reaction at the positive electrode (anode).

........O2– → ............... + ...............
[3]

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3a4 marks

The uses of a metal are determined by its properties.

Foods which are acidic can be supplied in aluminium containers.

 

aluminium-container

 

Explain why the acid in the food does not react with the aluminium.

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3b3 marks

Explain why overhead electrical power cables are made from aluminium with a steel core.

-IC38Te6_aluminium-cable

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45 marks

Extended tier only

Iron is extracted from its ore, hematite, in the blast furnace.

screen-shot-2022-09-12-at-14-21-23

Describe the reactions involved in this extraction.

Include one equation for a redox reaction and one for an acid/base reaction.

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5a1 mark

Aluminium and iron are extracted from their ores by different methods.

Aluminium is extracted from its purified oxide ore by electrolysis.

screen-shot-2022-09-14-at-14-45-29

What is the name of the ore of aluminium which consists mainly of aluminium oxide?

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5b1 mark

The electrodes are both made of the same substance.

Name this substance.

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5c2 marks

Iron is extracted from its oxide ore by reduction using carbon in a blast furnace.

screen-shot-2022-09-14-at-15-03-50
i)
Place the elements aluminium, carbon and iron in order of reactivity with the least reactive element first.
[1]
ii)
Use your answer to (e)(i) to explain why iron is extracted by reduction using carbon but aluminium is not.
[1]

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5d1 mark

What is the name of the ore of iron which consists mainly of iron(III) oxide?

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5e4 marks

Extended tier only

Write balanced equations for the reactions occurring in the blast furnace which involve

i)
The complete combustion of coke (carbon)
[1]
ii)
The production of carbon monoxide from carbon dioxide
[1]
iii)
The reduction of iron(III) oxide
[1]
iv)
The formation of slag
[1]

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6a4 marks

Iron is extracted from the ore hematite in the Blast Furnace.

screen-shot-2022-09-14-at-20-26-09

The coke reacts with the oxygen in the air to form carbon dioxide.

C + O2 → CO2

i)
Explain why carbon monoxide is formed higher in the Blast Furnace.
[2]
ii)
Write an equation for the reduction of hematite, Fe2O3, by carbon monoxide.
[2]

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6b6 marks

Limestone decomposes to form two products, one of which is calcium oxide.

 
i)
Name the other product
[1]
 
ii)
Calcium oxide reacts with silicon(IV) oxide, an acidic impurity in the iron ore, to form slag. Write an equation for this reaction.

[2]

iii)
Explain why the molten iron and the molten slag form two layers and why molten iron is the lower layer.

[1]

iv)
Suggest why the molten iron does not react with the air.

[2]

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6c2 marks

Iron and steel rust. Iron is oxidised to hydrated iron(III) oxide, Fe2O3.2H2O, which is rust.

i)
Name the two substances which cause iron to rust.
[1]

ii)
Explain why an aluminium article coated with aluminium oxide is protected from further corrosion but a steel article coated with rust continues to corrode.
[1]

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6d7 marks

Extended tier only

There are two electrochemical methods of rust prevention.

i)
The first method is sacrificial protection. Explain why the steel article does not rust.
screen-shot-2022-09-14-at-20-54-02
[4]
ii)
The second method is to make the steel article the cathode in a circuit for electrolysis. 
screen-shot-2022-09-14-at-20-54-08
Mark on the diagram the direction of the electron flow.

[1]

iii)
The steel girder does not rust because it is the cathode. Reduction takes place at the cathode. Give the equation for the reduction of hydrogen ions.

[2]

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