Metals & Their Extraction (WJEC GCSE Chemistry)

Exam Questions

5 hours36 questions

Easy

Medium

Hard

1a3 marks

The bar chart below shows the percentage of the three main gases in air.

q3a-wjec-gcse-chemistry-june-2015-1f

Choose from the box below the names of gases A, B and C.

argon	chlorine	hydrogen
methane	nitrogen	oxygen

A ...................................................

B ...................................................

C ...................................................

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1b4 marks

Air is one of the raw materials used in the extraction of iron from iron ore in the blast furnace. The following flow diagram summarises the process.

q3b-wjec-gcse-chemistry-june-2015-1f

Give the names of

[2]

raw material X, .............................................

product Y. ....................................................

ii)

Name the gas present in the air which is used up during combustion inside the blast furnace.

[1]

iii)

Balance the following symbol equation which represents a reaction that takes place in the blast furnace.

[1]

Fe₂O₃ + 3CO $\overset{}{\to}$ $□$ Fe + $□$ CO₂

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1a4 marks

The diagram shows the apparatus a teacher used to demonstrate what happens when an electric current is passed through molten lead bromide.

q4a-wjec-gcse-chemistry-june-2022-2f

Lead bromide contains the ions Pb²⁺ and Br ^–.

Underline the correct formula of lead bromide.

[1]

Pb₂Br PbBr PbBr² PbBr₂

ii)

Give the state (solid, liquid or gas) of the lead bromide during the process.

[1]

iii)

Name the orange gas formed at the anode. ...................................

[1]

iv)

During the process each lead ion, Pb²⁺, gains two electrons forming a lead atom at the cathode.

[1]

Tick (✓) the box next to the equation for the reaction at the cathode.

Pb + 2e^– → Pb²⁺ $□$

Pb²⁺ – 2e^– → Pb $□$

Pb²⁺ + 2e^– → Pb $□$

Pb – 2e^– → Pb²⁺ $□$

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1b4 marks

Iron is extracted from its ore in the blast furnace. The diagram shows the materials which enter and leave the furnace.

q4b-wjec-gcse-chemistry-june-2022-2f

Underline the correct word(s) in the brackets to complete each sentence.

[3]

The furnace is heated by burning (coke/iron/iron ore).

Hot air provides (waste gases/oxygen/slag) for burning to take place.

Impurities are removed by adding (steel/hot air/limestone) to the furnace.

ii)

The word equation shows the main reaction taking place in the blast furnace.

iron(III) oxide + carbon monoxide → iron + carbon dioxide

Give the letter next to the products which correctly balance the symbol equation for this reaction.

[1]

q4b2-wjec-gcse-chemistry-june-2022-2f

Letter .............................

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1c5 marks

Chemists have designed a wide variety of alloys for different uses.

Some alloys contain iron and carbon only, whereas others contain additional metals.

The table shows the composition and properties of some alloys.

Alloy	Composition	Properties
mild steel	iron plus 0.15–0.30% carbon	malleable (easy to bend), ductile (easy to pull into wire) and soft (easy to scratch)
high carbon steel	iron plus 0.70–1.50% carbon	strong, brittle and hard
cast iron	iron plus 2.00–5.00% carbon	very strong, very brittle and very hard

Use only the information in the table above to answer parts (i)–(iii).

Name the alloy that contains the least amount of carbon.

[1]

ii)

Underline the effect of increasing the percentage (%) of carbon in these alloys.

[1]

strength decreases	hardness decreases
softness increases	brittleness increases

iii)

Give the property of mild steel which makes it useful for making car bodies.

[1]

iv)

Diagrams A, B and C are models showing the arrangement of atoms in pure iron and in two alloys, but not necessarily in that order.

Choose the letter of the model which best represents cast iron. Give the reason for your choice.

[2]

q4c-wjec-gcse-chemistry-june-2022-2f

Letter ..............................

Reason ......................................................................

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2a7 marks

Joe, Alex and Megan were asked to investigate the temperature rise when four metals were added to excess copper(II) sulfate solution. of each metal was added to separate 50 cm³ samples of copper(II) sulfate solution.

The temperature rise for each reaction was measured.

q5a-wjec-gcse-chemistry-june-2022-2f

Their results are shown in the table below.

Metal	Temperature rise (°C)
magnesium	47
calcium	54
zinc	38
iron	25

Draw a bar chart on the grid to show the results. One bar has been drawn for you.

[2]

q5a1-wjec-gcse-chemistry-june-2022-2f

ii)

Put the four metals in order of reactivity.

[1]

Most reactive .................................................................................
.................................................................................
.................................................................................
Least reactive .................................................................................

iii)

The temperature rise for each metal was lower than expected. The students were asked to suggest how the apparatus could be improved so that the temperature rise recorded for each metal was closer to the expected value.

Joe suggested wrapping the polystyrene cup in cotton wool.
Megan suggested putting a lid on the polystyrene cup.
Alex suggested using a cup made from copper.

Choose which student’s suggestion would not result in the temperature rises being closer to the expected value. Explain your choice.

[2]

Student ..................................................................................................

Reason ..................................................................................................

iv)

Complete the equation for the reaction between magnesium and copper(II) sulfate solution.

[2]

Mg + CuSO₄ →............................................ + .............................................

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2b1 mark

The students repeated the experiment using chromium and recorded a temperature rise of 30°C.

What does the temperature rise of 30°C tell you about the reactivity of chromium compared to the four metals in part (a)?

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2 marks

The energy given out by the reaction can be calculated using the formula below.

energy given out (J) = volume of solution (cm³) × 4.2 × temperature rise (°C)

Calculate the energy given out during the displacement reaction between iron and copper(II) sulfate solution.

Energy given out = ..........................J

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6a5 marks

Iron is extracted from its ore in the blast furnace.

q6a-wjec-gcse-chemistry-june-2019-2h

Use information from the diagram and your knowledge to answer parts (i) and (ii).

Write a balanced symbol equation for reaction 2.

[2]

ii)

Describe the two-stage process to form slag.

[3]

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6b3 marks

Iron(III) oxide reacts with dilute hydrochloric acid forming iron(III) chloride and water.

Balance the symbol equation for this reaction.

[1]

Fe₂O₃(s) + $□$ HCl(aq) $\overset{}{\to}$ $□$ FeCl₃(aq) + $□$ H₂O(l)

ii)

Sodium hydroxide solution can be used to detect the presence of aqueous iron(III) ions.

The symbol equation below represents the reaction occurring between solutions of sodium hydroxide and iron(III) chloride.

3NaOH(aq) + FeCl₃(aq) $\overset{}{\to}$ 3NaCl(aq) + Fe(OH)₃(s)

Write the ionic equation for the formation of the precipitate.

[2]

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6c4 marks

Steel manufacture in the UK

One of the major steelmaking processes used today in the UK is the Basic Oxygen Furnace, BOF. The raw materials for the BOF are cast iron from a blast furnace and scrap steel. Oxygen (>99.5% pure) is “blown” into the BOF at supersonic speed. The impurities are oxidised producing great quantities of heat which melts the scrap steel.

Steel can be described in general terms as iron containing small amounts of carbon, to make it tougher and more ductile. There are many types of steel, each with its own specific chemical composition and properties to meet the needs of the many different applications. Figure 1 below shows the relationships between the carbon content of steel and its ductility, tensile strength and hardness.

q6c2-wjec-gcse-chemistry-june-2019-2h

Figure 1

Ductility is a material’s ability to be pulled into a wire.

Tensile strength is a measurement of the force required to pull something such as wire to the point where it breaks.

Hardness is a measure of how resistant a material is to permanent shape change when a compressive force is applied.

Figure 2 shows the percentage of carbon in various alloys of iron.

Name of alloy	Percentage of carbon
low carbon steel	0.0 – 0.6 %
medium carbon steel	0.6 – 0.8 %
high carbon steel	0.8 – 1.3 %
very high carbon steel	1.3 – 1.6 %

Figure 2

Tick (✓) the box next to the statement which best describes one way that production costs are reduced.

[1]

high purity oxygen is used	$□$
impurities are oxidised forming heat	$□$
oxygen is blasted in at supersonic speed	$□$
scrap steel is used in the process	$□$

ii)

Tick (✓) the box next to the statement which best describes the effect of increasing the percentage of carbon in steel from 0% to 0.45%.

[1]

ductility increases, hardness increases	$□$
tensile strength increases, ductility increases	$□$
ductility decreases, tensile strength increases	$□$
hardness increases, tensile strength decreases	$□$

iii)

A steel manufacturer wants to design an alloy with a high tensile strength but low ductility. Tick (✓) the box next to the approximate value for the percentage of carbon that should be included.

[1]

0.2

□

0.6

□

1.0

□

1.5

□

iv)

Name the alloy which is the most easily pulled into a wire and withstands the least compressive force.

[1]
..............................................................................................................

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7a4 marks

The diagram shows where substances enter and leave the blast furnace in the extraction of iron from iron ore.

q1-paper-2f-june-2018-wjec-gcse-chemistry

coke

slag

iron

limestone

iron ore

Use the substances in the box to complete the following sentences.

[3]

The three raw materials which enter the furnace at A are .............................. , .................................. and .............................. .

Product B is ............................... and product C is ..................................

ii)

One reaction that takes place in the furnace is

iron(III) oxide + carbon monoxide → iron + carbon dioxide

Underline the element which is removed from the iron(III) oxide during the reaction.

[1]

iron

oxygen

carbon

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7b2 marks

Statements D, E and F show the three steps needed to prepare a sample of copper(II) chloride in the laboratory. The steps are not in the correct order.

D filter to remove excess copper(II) oxide

E leave the copper(II) chloride solution to evaporate at room temperature

F add excess copper(II) oxide to dilute hydrochloric acid

Complete the flow chart by putting the letters in the correct order.

$□$	$\to$	$□$	$\to$	$□$
first step				last step

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7c6 marks

The diagram shows the apparatus used to obtain copper from copper(II) chloride solution.

q1c-paper-2f-june-2018-wjec-gcse-chemistry

electrolyte

electrodes

electricity

electrolysis

Choose words from the box to complete the following sentences.

[2]

The breaking down of copper(II) chloride solution using an electric current is called ............................... .
Electric current enters and leaves the copper(II) chloride solution by the .................................. .

ii)

By drawing arrows on the diagram, show the direction in which the circled ions move during the process.

[1]

iii)

The reaction occurring at the cathode is:

Cu²⁺	+	2e^-	$\to$	Cu
copper(II) ion				copper atom

Put a tick (✔) in the box next to what e^– represents in the equation.

[1]

electricity	$□$
electron	$□$
ion	$□$
atom	$□$

II.

Copper(II) ions, Cu²⁺, are removed from the solution during the process.

Put a tick (✔) next to the statement which describes what, if anything, happens to the colour of the copper(II) chloride solution.

[1]

the blue solution turns darker	$□$
the blue solution turns paler	$□$
the blue solution turns yellow	$□$
nothing happens to the colour of the blue solution	$□$

iv)

Put a tick (✔) next to the gas which is formed at the anode.

[1]

oxygen	$□$
hydrogen	$□$
chlorine	$□$

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8a4 marks

When a mixture of iron(III) oxide and aluminium powder (Thermit mixture) is heated, there is a violent reaction. The reaction is carried out in a tube surrounded by a mound of sand because the temperature reaches 2500°C. A bead of iron is recovered from the sand. The picture below shows the reaction taking place in a darkened room.

q8a-paper-2f-june-2018-wjec-gcse-chemistry

Give the reason why the iron formed in the reaction is molten.

[1]

ii)

Complete and balance the symbol equation for this reaction.

[1]

Fe₂O₃ + 2Al

\to

□

Fe + ................

iii)

State which of the substances is oxidised. Give the reason for your choice.

[1]

iv)

When a mixture of magnesium oxide and aluminium powder is heated, there is no reaction.
List iron, magnesium and aluminium in order of reactivity.

[1]

Most reactive ...........................

Least reactive ..........................

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8b4 marks

Some metals are more reactive than others. A more reactive metal displaces a less reactive metal from its compounds.

A student was given tin, iron, copper and zinc and solutions of the metal sulfates. Using a dropping pipette, she put a little of one of the sulfate solutions in four of the depressions of the dropping tile. She did this for each solution in turn. She then put a piece of metal foil in each of the solutions, as shown below.

q8b-paper-2f-june-2018-wjec-gcse-chemistry

Put a tick (✔) next to the question which best describes the investigation the student is carrying out.

[1]

Which displacement is the most exothermic?	$□$
Which metal can displace copper from solution?	$□$
What is meant by the reactivity series?	$□$
What are the positions of the four metals in the reactivity series?	$□$

ii)

The student recorded the results by putting a tick (√) next to a mixture which showed signs of a reaction and a cross (X) next to a mixture which showed no signs of a reaction.

The student concluded that:
   tin displaces copper
   iron displaces tin
   iron displaces copper
   zinc displaces iron

Give the letter of the tile below which shows the results she recorded.

[1]

Letter ...............................

q8bii-paper-2f-june-2018-wjec-gcse-chemistry

iii)

Another student said that not all of the tests were necessary. Give one example of a test not needed. Explain your choice.

[2]

Example ............................
Explanation .......................

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8c3 marks

Copper displaces silver from a solution of silver nitrate, AgNO₃, to form copper(II) nitrate solution.

Describe one change the student would see during this displacement reaction.

[1]

ii)

Write a balanced symbol equation for this reaction.

[2]

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4a3 marks

Three students individually investigated the mass of copper formed when increasing amounts of magnesium powder were added to 50 cm³ of copper(II) sulfate solution.

q7a-wjec-gcse-chemistry-june-2014-1h

Each pupil added 0.10 g of magnesium to 50 cm³ of copper(II) sulfate solution and stirred the mixture until no more magnesium remained.
They filtered, dried and weighed the copper formed.
They repeated the experiment using 0.15, 0.20 and 0.25 g of magnesium powder and a new 50 cm³ of copper(II) sulfate solution each time.
The results are shown below.

Mass of magnesium added (g)	Mass of copper formed (g)
Mass of magnesium added (g)	Student A	Student B	Student C	Mean
0.10	0.15	0.10	0.17	0.14
0.15	0.25	0.21	0.23	0.23
0.20	0.37	0.36	0.32	0.35
0.25	0.37	0.42	0.38	0.39

The graph opposite shows the masses of copper that should be formed.

On the same grid plot the mean mass of copper formed against the mass of magnesium added. Draw a suitable line.

q7a2-wjec-gcse-chemistry-june-2014-1h

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4b1 mark

Describe the main difference between the expected graph and the one plotted using the experimental results.

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4c2 marks

Suggest two possible reasons for the difference in the graphs.

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4d3 marks

On Anglesey there is a large copper mine called Parys Mountain. Unwanted rock from the mining process has been dumped forming waste tips. As rainwater passes through the waste tips it dissolves copper salts. One of the salts is copper(II) sulfate.

During the 18th century large shallow pits were dug all over the mountain. These filled with rainwater. Scrap iron was placed into the water and after a few months the pits were drained and a copper-rich solid sludge was collected.

q7d-wjec-gcse-chemistry-june-2014-1h

Explain the reaction taking place in the pits.

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4e2 marks

Copper is a good electrical conductor and is therefore used to make electrical wiring.
Give a different property of copper and one use which relies on this property.

Property .....................................................

Use ............................................................

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low density	resists corrosion
good electrical conductor	good thermal conductor

A less reactive metal displaces a more reactive metal from its compounds
A more reactive metal displaces a less reactive metal from its compounds
Displacement reactions require heating
Displacement reactions are easier to see when they are in solution

To obtain more aluminium
To increase the melting point of the mixture
To decrease the melting point of the mixture
To use less aluminium oxide

Most reactive:	____________________
	____________________
	____________________
Least reactive:	____________________

Reduction
Oxidation
Neutralisation
Displacement
Combustion

Carbon is reduced	$□$
Tin is oxidised	$□$
Tin oxide is reduced	$□$
Carbon dioxide is oxidised	$□$

The energy used to extract metals is greater than that used in recycling them	$□$
The difference between the energy used to extract and the energy used to recycle is the greatest	$□$
The energy used in recycling is less than for copper but greater than for steel	$□$

Current (A)	Mass of copper deposited (g)
0.0	0.00
0.5	0.16
1.0	0.30
1.5	0.43
2.0	0.60

hot air	coke	iron	iron ore
limestone	slag	steel	waste gases

Mass of magnesium used (g)	Mass of copper formed (g)
0.05	0.14
0.10	0.27
0.15	0.40
0.20	0.53
0.25	0.66

Colour	red	orange	yellow	green	blue	navy blue	purple
pH	0-2	3-4	5-6	7	8-9	10-12	13-14

Alloy of iron	Percentage of carbon present in the alloy (%)
wrought iron	0.1
mild steel	0.3
high-carbon steel	0.9
cast iron	3.6