Transition Metals, Alloys & Corrosion (Edexcel GCSE Chemistry)

Exam Questions

3 hours24 questions
1a2 marks

Alloys are mixtures of two or more metals.

Alloy steels are formed when other metals are mixed with iron.

Cutlery is made of stainless steel.

Give two reasons why cutlery is made of stainless steel rather than iron. 

1b1 mark

Brass is an alloy of copper.
Figure 3 shows the brass pins of an electric plug. 

fig-3-q2b-1cho-1f-paper-1-june-2019
Figure 3

Brass is harder than copper.
Give a reason why using a harder substance for the pins is an advantage. 

1c
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5 marks

Magnalium is an alloy of magnesium and aluminium.
It is often used for aircraft parts.

i)
Figure 4 shows information about pure aluminium and magnalium.

substance density in g cm-3 relative strength resistance to corrosion
aluminium 2.7 low high
magnalium 2.0 high very high

Figure 4

Explain, using the information in Figure 4, why magnalium, rather than pure aluminium, is used for aircraft parts. 

(3)

ii)
63.0 g of magnalium contains 3.15 g of magnesium.
Calculate the percentage by mass of magnesium in the magnalium. 
(2)

percentage of magnesium in the magnalium =.........................

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2a1 mark

Transition metals and group 1 metals have many properties in common because they are all metals.

However some properties of transition metals are different from properties of group 1 metals.

Which is a property of transition metals but not of group 1 metals?  

  A good conductor of electricity 
  B high melting point 
  C malleable 
  D shiny when cut or polished 
2b2 marks

Copper is a transition metal.

Magnesium reacts with copper sulfate solution to form copper and a solution of magnesium sulfate.
Magnesium sulfate solution is colourless.

Describe two changes you would see during this reaction. 

2c
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5 marks

Rusting is the corrosion of iron.

 
i)
Water is one of two substances needed for iron to rust.

Give the name of the other substance needed for iron to rust. 

(1)

ii)
The rate of rusting can be increased by using sea water.

Describe a simple experiment to compare how much an iron nail rusts in sea water when compared to water. 

(3)

iii)
Rusting can be prevented by galvanising iron which involves coating the iron with a layer of zinc.

A small iron bucket was galvanised. The surface area of the bucket was 0.68 m2.

Calculate the mass of zinc required to coat the surface of the bucket with a layer of zinc of 200 g m-2.  
(1)
mass of zinc = ............................. g 

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3a2 marks

In a hydrogen-oxygen fuel cell, hydrogen and oxygen react at the electrodes.

The overall reaction occurring in this fuel cell is a reaction of hydrogen with oxygen.

Write the balanced equation for this reaction.

3b2 marks

The electrodes of a fuel cell are in contact with water and air. 

The electrodes are made of platinum rather than iron.

i)
State why iron is not a suitable metal for the electrodes of the cell.                         

(1)

ii)
Platinum acts as a catalyst.

State, in terms of its position in the periodic table, why you would expect platinum to act as a catalyst.

(1)

3c2 marks

Some metal objects are electroplated.

State two reasons for electroplating a metal object.

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4a1 mark

Gold is a transition metal.

 Which is a property of gold?

A Forms white coloured compounds
B High melting point
C Low density
D Poor conductor of electricity
4b1 mark

Complete the sentence:

Gold is often mixed with other metals to form an ………………

4c2 marks

18 carat gold contains 75% gold.

Calculate the mass of gold in 2 kg of 18 carat gold.

4d2 marks

18 carat gold is normally used for jewellery instead of pure, 24 carat gold.

Suggest a reason why.

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5a2 marks

Iron can rust when it is exposed to water and oxygen.

Is rusting a chemical or physical change?

Give a reason for your answer.

5b2 marks

Painting an iron object can stop the object from rusting.

Explain why.

5c2 marks

Iron nails are often covered in a layer of zinc.
This is called galvanising.
Even if the zinc layer is scratched, the iron is still protected against rusting.

Use words from the box to complete the sentences about how this works.

corrodes            less               more                 rusts     

 Zinc is ………….. reactive than iron so it ………………instead.

5d1 mark

Other than painting and galvanising, give one other way that iron can be protected against rusting.

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1a2 marks

Give two advantages for electroplating some metal objects.

1b
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2 marks

Solder is an alloy of tin and lead.

A sample of a solder was made by mixing 22.5 g of lead with 15.0 g of tin.

Calculate the percentage of tin in this solder.

percentage of tin = ...........................................................................................%

1c3 marks

The rusting of an iron nail was investigated by setting up three test tubes, as shown in Figure 6.

fig-6-q5c-1cho-1f-specimen-2018
Figure 6

State and justify the result you would see in each tube after one week.

1d2 marks

An iron bucket is coated in zinc.

Over many years of use, the iron bucket has been scratched and left outside in the rain.
Although some of the zinc coating has been removed to expose iron, the iron bucket has not rusted.

Explain why the iron has not rusted.

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21 mark

Transition metals are located in the middle of the periodic table and have certain properties.

Which two properties do most transition metals have? 

      Property 1 Property 2
  A soft forms colourless compounds
  B high melting points low densities
  C high densities form coloured compounds
  D form ions with multiple charges do not conduct electricity

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3a1 mark

Alloy steels are made when iron is alloyed with other transition metals such as cobalt and chromium.

Which row of the table shows the typical properties of a transition metal?

      used as a catalyst density colour of metal chloride
  A Yes high colourless
  B No low colourless
  C Yes high coloured
  D No low coloured

3b2 marks

Figure 1 shows the chain on a bicycle.

eaDY8R8l_fig-1-q1b-1cho-1h-paper-1-june-2018

Figure 1

Explain how lubricating the chain with oil prevents corrosion of the steel chain.

3c2 marks

Iron fences can be galvanised by coating them with a layer of zinc.
When the layer of zinc is scratched exposing the iron to the weather, the iron does not rust.

Explain why the exposed iron does not rust.

3d2 marks

Metals have high melting points.

Explain, in terms of their structure and bonding, why metals have high melting points.

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4a1 mark

Many metals corrode.

When a metal corrodes

  A the metal reacts with nitrogen
  B the metal reacts with another metal
  C the metal element decomposes
  D the metal is oxidised

4b5 marks

An experiment is carried out to see if magnesium ribbon wrapped around a piece of iron rod has an effect on the rate at which the iron rod rusts.

The apparatus is shown in Figure 4.

 
fig-4-q7b-1cho-1h-paper-1-june-2019
 
Figure 4
 
The method used is
  • an iron rod, with magnesium ribbon wrapped around it, is placed in a boiling tube labelled A
  • 10 cmwater from a measuring cylinder is poured into this boiling tube
  • an identical rod but with no magnesium ribbon wrapped around it is placed in a second boiling tube labelled B
  • 10 cm3 water from a measuring cylinder is poured into this boiling tube.
 
Both boiling tubes are left for a few days.
  
i)
Explain why iron rod rather than stainless steel rod is used in this experiment.
 
(2)
 
ii)
State why it is not necessary to use a pipette to measure out 10 cm3 water in this experiment.

(1)

iii)
After a few days the two boiling tubes were examined.
 
The results are shown in Figure 5.
 
boiling tube A

the appearance of the iron rod is unchanged

the magnesium has started to disappear

boiling tube B a small amount of brown deposit has formed around the rod
 
Figure 5
 
Explain the results of this experiment.
 
(2)
4c2 marks

Hydrazine, N2H4, reacts with oxygen.

 
N2H4 + O2 → N2 + 2H2O
 

A metal in water corrodes faster than an identical piece of metal in the same volume of water containing dissolved hydrazine.

 

Use the information to explain how hydrazine slows corrosion.

4d3 marks

Higher Only

Ammonia is used to make hydrazine.

In the industrial process to manufacture ammonia, nitrogen and hydrogen are combined in the presence of an iron catalyst.

 
N2 + 3H2 rightwards harpoon over leftwards harpoon 2NH3 
 
i)
State the name of the industrial process to manufacture ammonia.
 
(1)

ii)
Predict the effect that adding the catalyst has on the rate of attainment of equilibrium.
 
(1)

iii)
Predict the effect that adding the catalyst has on the equilibrium yield of ammonia.
 
(1)

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51 mark

Nitrogen and water are produced when ammonia reacts with oxygen. 

A metal oxide catalyst is used to speed up the rate of reaction.

Which of the following metal oxides would most likely be used for this reaction?

  A Na2O
  B Li2O
  C Al2O3
  D Cr2O3

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6a
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1 mark

Transition metals have many uses.

The pie chart in Figure 6 shows the uses of one transition metal.

fig-6-q5a-1cho-1f-paper-1-nov-2020

Figure 6

Calculate the percentage of this transition metal used in construction.

percentage of this transition metal used in construction = ..................................................

6b3 marks

Figure 7 shows five statements about iron.

Put ticks (✓) in the boxes in Figure 7 to show which statements are true and which statements are false.
The first one has been done for you.

  true false
iron is a poor conductor of heat   ✓
iron can act as a catalyst    
iron forms compounds that are coloured    
iron has a low density    
iron has a very high melting point    

Figure 7

6c
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3 marks

Most iron produced is converted into alloys of iron.

i)
State why alloys have more uses than pure metals.
(1)
ii)
An alloy of iron contains 0.40% of molybdenum.

Calculate the mass of molybdenum contained in a 30 g sample of this alloy of iron.
(2)

mass of molybdenum = ................................................. g

6d2 marks

Many transition metals are used to make the reactants in chemical cells.

Figure 8 shows a graph of the voltage produced by a chemical cell as it is used in a torch for many hours.

fig-8-q5d-1cho-1f-paper-1-nov-2020
Figure 8


Suggest an explanation for the shape of the graph.

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7a5 marks

Iron rusts when it is left in certain conditions.

i)
Figure 9 shows the apparatus used to investigate the rusting of some iron nails.

fig-9-q7ai-1cho-1f-paper-1-nov-2020

Figure 9

Explain why the iron nail in tube A would rust but the iron nails in tubes B and C would not rust.

(3)

ii)
Magnesium is more reactive than iron.
Figure 10 shows an iron nail with a strip of magnesium wrapped around it, placed in some water.
The tube was left for a few days.

fig-10-q7aii-1cho-1f-paper-1-nov-2020

Figure 10

State what would happen to this iron nail.

(1)

iii)
When iron rusts, a brown solid forms on the surface of the iron.

What happens to the iron as the rust forms?
(1)
  A the iron is hydrated
  B the iron is neutralised 
  C the iron is oxidised 
  D the iron is reduced 
7b1 mark

Give one reason why metals are electroplated.

7c6 marks

The pure metals aluminium, copper and gold and the alloys brass and magnalium are used to make many useful articles.

The way in which these metals and alloys are used is related to their properties, such as their density, electrical conductivity, resistance to corrosion and strength.

State some uses of aluminium, copper, gold, brass and magnalium and explain how each use is related to their properties.

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81 mark

Brass is an alloy of which metals?

  A Copper and tin
  B Silver and copper
  C Copper and zinc
  D Iron and copper

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9a2 marks

Alloys of gold are often used to make jewellery.
The purity of gold is measured in carats.
Different alloys of gold have different carats.

Figure 1 shows the percentage of different metals in two samples of gold.

  percentage of metal
gold silver copper
18 carat gold 75.0 15.0 10.0
24 carat gold 100.0 0.0 0.0

Figure 1

Explain why 18 carat gold is stronger than 24 carat gold.

You may use diagrams to help your answer.

9b
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3 marks

Figure 2 shows the relationship between the purity of gold in carats and the percentage of gold in the alloy.

fig-2-q1b-1cho-1h-paper-1-nov-2020
Figure 2

A necklace with a mass of 5.0 g was found to contain 2.9 g of gold.

Determine the purity of the gold necklace in carats.
Show your working.

purity of the gold necklace = ............................... carats
9c
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2 marks

Higher Tier Only 

A gold ring contains 3.94 g of gold.

Calculate the number of gold atoms in the ring.
(relative atomic mass: Au = 197,
Avogadro constant = 6.02 × 1023)

Show your working.

number of gold atoms = ...........................................

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101 mark

Why are alloys harder than the pure metals from which they are made?

  A There are stronger bonds between the atoms
  B The atoms are all the same size 
  C The layers of atoms are distorted
  D The properties of each element have combined

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11a2 marks

This question is about the metal gold.

i)
Gold can be hammered into shape.

State the name of this property.

(1)

ii)

Gold alloys can be used to repair teeth.

One reason that gold alloys are used is that they can be hammered into shape.

Give one other reason why gold alloys are used to repair teeth.

(1)

11b
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3 marks

A gold alloy contains 78% gold by mass.

Calculate the mass of gold in 2.00 kg of this alloy.

Give your answer in grams.

mass = .............................................................. g

11c2 marks

A substance used to purify gold is kept in a container.

There are some hazard symbols on the container.

Draw one straight line from each hazard symbol to its meaning.

fig-q7c-1cho-1f-paper-1-nov-2021

11d6 marks

Some gold alloys contain copper.


Copper reacts with oxygen when heated.

copper + oxygen → copper oxide

A teacher calculates that 1.20g of copper reacts completely with oxygen to form 1.50g of copper oxide.

A student heats 1.20g of copper pieces in a container.
Then they heat 1.20g of copper powder in another container.
After heating, the mass of the solid in the containers is found.

The results are shown in Figure 7.

  colour before
heating
mass before
heating in g
time of heating
in mins
colour after
heating
mass after
heating in g
copper pieces red-brown 1.20 5 black 1.28
copper powder red-brown 1.20 10 black 1.42


Figure 7

Explain the observations and give reasons why the masses after heating are less than expected.

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12a3 marks

Aluminium alloys are used instead of pure aluminium in aircraft manufacture.

Explain, in terms of the arrangement of metal particles, why aluminium alloys are stronger than pure aluminium.

12b2 marks

A 695.0 g sample of an aluminium-magnesium alloy contains 2.00% by mass of magnesium.

Calculate the mass of aluminium in this sample.

mass of aluminium = .........................................g
12c4 marks

Figure 12 shows a graph of the relative strength of aluminium-magnesium alloys
when the percentage by mass of magnesium in the alloy is changed.

fig-12-q10c-1cho-1f-paper-1-nov-2021

Figure 12

i)
Describe what Figure 12 shows about the relative strength of these alloys when the percentage by mass of magnesium changes.

(2)

ii)
Determine, using Figure 12, the percentage by mass of aluminium in an aluminium-magnesium alloy with a relative strength of 103.
(2)
percentage by mass of aluminium = ...............................................................
12d2 marks

Metal objects can be electroplated with gold.

Give two reasons why metal objects are electroplated with gold.

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131 mark

Complete the sentence on corrosion.

When a metal corrodes

  A The metal decomposes
  B The metal reacts with carbon dioxide
  C The metal begins to rust
  D The metal is oxidised

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14a2 marks

Higher Only


Objects made from transition metals are sometimes coated with a thin layer of another transition metal to improve their appearance and to protect against corrosion.

Figure 10 shows equipment that can be used to electroplate an iron spoon with silver.
fig-10-q5a-1cho-1h-specimen-2018
Figure 10

i)
Which row of the table correctly shows the charge on the silver rod electrode and the type of reaction occurring at this electrode?
(1)
      charge type of reaction
  A negative oxidation
  B negative  reduction
  C positive oxidation
  D positive reduction

ii)
Silver metal is deposited on the spoon.

Which half-equation represents this reaction?
(1)
  A Ag + e → Ag+
  B Ag → Ag+ + e
  C Ag+ + e → Ag
  D Ag+ → Ag + e 

14b1 mark

The voltage of a cell is 1.5V.

Give a reason why this voltage of the cell decreases when the cell is left connected in a circuit.

14c2 marks

Duralumin is an alloy of aluminium and copper.

The radii of the aluminium and copper atoms are shown in Figure 11.

  radius of atom/m
aluminium 1.43 × 10−12
copper 1.27 × 10−12

Figure 11

Explain why copper added to aluminium to form the alloy makes the alloy stronger than pure aluminium.

14d
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2 marks

Gold is often alloyed with other metals when it is used to make jewellery.

The proportion of gold in a piece of gold jewellery is measured in carats.

Pure gold is 24 carats.

A 9 carat gold ring has a mass of 12 g.

Calculate the mass of gold in this ring.

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1a6 marks

Pure metals are often converted into more useful alloys.
For example, aluminium is converted into an alloy used in aircraft, iron is converted into an alloy used in cutlery and gold alloys are used in jewellery.
These processes of alloying change the structures of the metals.

Some properties of pure aluminium, iron and gold are shown in Figure 12.

  density
in g cm-3
malleability relative
strength
aluminium 2.70 easy to bend low
iron 7.75 easy to bend low
gold 19.3 easy to bend low
Figure 12

Explain how alloying changes these pure metals to make the alloys more suitable for the given uses.

1b4 marks

Iron objects can corrode when exposed to the atmosphere.

i)
Corrosion involves the oxidation of iron.
State what is meant by oxidation.
(1)
ii)
Painting iron objects prevents corrosion.
Explain why painting iron objects prevents corrosion.
(2)
iii)
Corrosion of iron objects can be prevented by painting them or by electroplating them.
State one other way of preventing the corrosion of iron objects.
(1)
1c2 marks

The apparatus shown in Figure 13 was used to electroplate a spoon with nickel.

fig-13-q7c-1cho-1f-paper-1-june-2018
Figure 13

i)
State to what the anode and cathode have to be connected in order to carry out the electroplating.
(1)
ii)
Predict the name of a substance that could be dissolved in water to form the electrolyte for this electroplating.
(1)

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2a3 marks

Pure iron is mixed with carbon and other metals to make alloys.

Explain, using the arrangement of metal particles, why iron alloys are stronger than pure iron.

2b2 marks

A stainless steel contains 0.10% carbon, 16.4% chromium, 19.8% nickel, 4.2% molybdenum and iron.

Calculate the percentage of iron in the alloy.

2c2 marks

Calculate the mass of molybdenum contained in a 30 g sample of this alloy.

2d1 mark

State why stainless steel, rather than pure iron, is used to make cutlery.

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3a3 marks

A student wanted to investigate what variables affect rusting.
They set up the three test tubes shown in Figure 1.
They left the tubes for five days.

edx-5-1h-q3a-rusting-experimentFigure 1

For each test tube, predict if you think the nail will rust.

Give a reason for each prediction.

3b1 mark

The student set up test tube A again but this time used a painted nail.

Explain why painting a nail will protect it from rusting.

3c3 marks

Aluminium forms a layer of aluminium oxide on its surface.
This protects it from corrosion.

Write a balanced symbol equation for this reaction.

3d1 mark

Other than its corrosion resistance, give one reason why aluminium is a good choice for making window frames.

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4a2 marks

Iron is a transition metal.
Iron is used to build bridges.

Evaluate using iron for this function.

4b1 mark

Iron objects can be covered with a layer of zinc to protect them from rusting.

Name this process.

4c2 marks

If a zinc-covered nail is scratched, the nail is still protected by sacrificial protection.

Explain how this works.

4d1 mark

Higher Only

During sacrificial protection zinc is oxidised to form zinc ions.

Write the half equation to show this.

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5a2 marks

Higher Only

A teacher used the apparatus in Figure 2 to explain how electroplating works.

edx-5-1h-q5a-electroplating

Figure 2 

The half equation for what happens at the copper rod is:

Cu → Cu2+ + 2e-

What type of reaction is this?

Give a reason for your answer.

5b2 marks

Higher Only

Explain what you would see happen to the iron nail.

Include a half equation in your explanation.

5c2 marks

Higher Only

Explain why the colour of the copper sulfate solution does not change during the experiment.

5d1 mark

Give one reason why electroplating is used.

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