AQA GCSE Chemistry: Combined Science

Topic Questions

4.1 Reactivity of Metals

1a2 marks

This question is about the reactions of metals with oxygen.

Complete the sentences.

      In terms of oxygen, ____________________ is the loss of oxygen.

      In terms of oxygen, ____________________ is the gain of oxygen.

1b1 mark

Name the compound formed when cobalt reacts with oxygen.

1c2 marks

Iron can react with oxygen to form iron (II) oxide.

2Fe + O2 → 2FeO

Iron can also react with oxygen to form iron (III) oxide

4Fe + 3O2 → 2Fe2O3 

Nickel can react with oxygen to form nickel(II) oxide or nickel (III) oxide.

Write two balanced symbol equations to show both reactions of nickel with oxygen.

1d1 mark

Nickel is below carbon in the reactivity series.

This means that carbon can be used to extract nickel from nickel (II) oxide.

Complete the word equation.

Nickel (II) oxide + carbon → _______________ + _______________ 

1e2 marks

The reaction of nickel (II) oxide with carbon is a redox reaction.

Is carbon oxidised or reduced? Explain your answer. 

      Carbon is ____________________

      Reason: ____________________

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2a2 marks

The reactivity series arranges metals in decreasing order of reactivity.

Name two non-metals that commonly appear in the reactivity series.

2b3 marks

Place the following metals in order from most reactive to least reactive.

gold iron lithium magnesium

Most reactive: ____________________
  ____________________
  ____________________
Least reactive: ____________________
2c1 mark

Sodium is above copper in the reactivity series.

This means that sodium could be used to extract copper from its ore.

2Na + CuO → Cu + Na2O

What type of reaction is this?

Tick (one box.

Reduction  
Oxidation  
Neutralisation  
Displacement   
Combustion  
2d1 mark

Suggest one reason why sodium is not used to extract copper from copper (II) oxide.

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3a2 marks

This question is about the reactions of metals with water and acid.

Some metals will react with cold water to produce the metal hydroxide and hydrogen.

One of the observations for more reactive metals can be a coloured flame.

Which metals can give a coloured flame when they react with cold water?

Tick () two boxes.

Aluminium   
Copper  
Potassium  
Sodium  
Zinc  
3b3 marks

Metals react with acid to produce a salt and water.

Draw one line from each acid to the salt that it forms when it reacts with a metal.

aqa-gcse-4-1e-q3b-acid-salt-matching-

3c5 marks

Choose words from this list to complete the word equations below.

chlorate sulfate sulfuric water
hydrochloric hydrogen hydroxide


potassium + water → potassium _______________ + _______________ 

magnesium + ____________ acid → magnesium ____________ + ____________ 

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4a1 mark

Displacement reactions can happen between a metal and a compound containing metal.

Which statement about displacement reactions is correct?

Tick (one box.

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  
4b4 marks

The reactivity of a metal can be used to determine how it is extracted from its ore.

Match the metal to its method of extraction.

aqa-gcse-4-1e-q3b-metal-extraction-matching

4c2 marks

Which metal cannot be extracted by reduction with carbon? Give a reason for your answer.

Circle the correct metal.

Aluminium Copper Zinc

 

Reason: ________________________________________

4d2 marks

The thermite reaction of aluminium with iron oxide produces the molten iron used to weld rail tracks together.

Use the balanced chemical equation to identify which chemical is reduced. Give a reason for your answer. 

2Al + Fe2O3 → 2Fe + Al2O3 

Chemical reduced: ________________________________

Reason: ________________________________________

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5a1 mark

Magnesium reacts with silver nitrate in a displacement reaction.

Complete the word equation for this reaction. 

magnesium + silver nitrate → _______________ + _______________ 

5b2 marks

Complete the sentences.

      In terms of electrons, ____________________ is the loss of electrons.

      In terms of electrons, ____________________ is the gain of electrons.

5c1 mark

Calcium, Ca, reacts with zinc (II) sulfate, ZnSO4, in a displacement reaction.

Complete the chemical symbol equation for this reaction.

Ca + ZnSO4 → _______________ + _______________

5d1 mark

The formula of the sulfate ion is SO subscript 4 superscript 2 minus end superscript.

What is the correct charge for a zinc ion in this reaction?

5e2 marks

Complete the ionic equation for the formation of calcium sulfate.

__________  +  SO subscript 4 superscript 2 minus end superscript  →  __________

5f1 mark

Write the half equation to show the calcium metal reacting to form the calcium ion in calcium sulfate.

_________   →  Ca2+  +  ________

5g2 marks

The half equation for the zinc ion in the calcium / zinc sulfate displacement reaction is:

Zn2+ + 2e → Zn

Does this half equation show oxidation or reduction? Give a reason for your answer.

      The half equation shows ___________________________

      Reason: ________________________________________

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1a2 marks

This question is about titanium.

Titanium is highly valued as a metal due to its high tensile strength, resistance to corrosion and high melting point. It is also as strong as steel but 45% lighter.

Titanium is most commonly produced by using the following batch process from its ore, rutile (titanium oxide). This process can take up to 17 days.

  1. Titanium oxide reacts with chlorine
  2. Titanium chloride is placed in a reactor with magnesium at 900 oC in a sealed container for 3 days 
  3. The reactor is allowed to cool
  4. The titanium and magnesium chloride are separated by hand  

Carbon cannot be used in the reactor as a replacement for magnesium, as there is no reaction. 

Explain what this suggests about the relative reactivities of carbon, magnesium and titanium.

1b
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3 marks

Titanium reactors produce about 41.67 kg of titanium per hour whereas iron blast furnaces produce about 20 000 tonnes of iron per hour.

Calculate how many times more iron is produced per hour. Show your working.

Give your answer to three significant figures.

1c4 marks

There are several applications where titanium is used instead of steel. However, the cost of titanium limits its uses.

Explain why titanium costs more than steel to produce.

1d1 mark

It is suggested that the titanium end product could be purified by washing it with water to remove the magnesium chloride.

Explain why this suggestion is not suitable.

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2a
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4 marks

This question is about displacement reactions.

In their first experiment, a student uses the following method to investigate the reaction between zinc and copper (II) sulfate solution.

Zn (s) + CuSO4 (aq) → Cu (s) + ZnSO4 (aq)

  1. Measure exactly 25.0 cm3 of 79.8 g / dm3 copper (II) sulfate solution into a polystyrene cup
  2. Record the initial temperature of the solution
  3. Add about 5 g of zinc powder
  4. Stir the mixture
  5. Record the highest temperature reached

Show that zinc is not the limiting reactant.

Relative atomic masses (Ar):     Zn = 65,     Cu = 63.5,     S = 32,     O = 16

2b2 marks

Describe two observations that you would expect to see during the displacement reaction between zinc and copper (II) sulfate.

2c2 marks

Explain whether the zinc is oxidised or reduced in this displacement reaction.

Your answer should include a half equation.

2d2 marks

In a second experiment, the student places 5 g of copper powder into a beaker containing nickel sulfate solution. 

No reaction occurs.

Explain why the order of reactivity for copper, nickel and zinc cannot be determined from these two experiments.

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3a1 mark

This question is about the reaction between lead (II) nitrate solution and potassium chromate solution.

Lead (II) nitrate solution and potassium chromate solution react to form a yellow precipitate of lead (II) chromate and potassium nitrate solution.

Complete the equation by adding the state symbols.

Pb(NO3)2 (___) + K2CrO4 (___) → PbCrO4 (___) + 2KNO3 (___)

3b2 marks

The formula of the chromate ion is CrO subscript 4 superscript 2 minus end superscript.

Explain why this reaction is not a redox reaction.

3c3 marks

Describe how a pure, dry sample of solid lead (II) chromate can be obtained at the end of the investigation.

3d1 mark

Lead nitrate was used in the production of many paints.

Suggest why lead nitrate has been replaced by titanium dioxide in the production of many paints. 

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4a1 mark

A student investigated the temperature change in displacement reactions between metals and iron sulfate solution.

The student’s results are shown in Table 1.

Table 1

Metal

Temperature increase in °C

Copper

0

Iron

0

Magnesium

30

Zinc

4


Explain what type of graph should be plotted from the student's results.

4b4 marks

Using the student's results, explain whether it is possible to rank the metals from most to least reactive or not.

4c4 marks

You have been asked to make one adaptation to the experiment so that you can find the position of an unknown metal in the reactivity series.

Describe the method, including your adaptation, to determine the position of an unknown metal in the reactivity series.

Your adapted method should give valid results.

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1a1 mark

This question is about oxides of metals.

Sodium oxide is produced when sodium is heated in oxygen. The balanced equation for the reaction is as follows:

4Na + O2 ⟶ 2Na2O

Why is this considered an oxidation reaction?

1b1 mark

In terms of oxygen, describe what happens to a substance that undergoes reduction?

1c1 mark

A student investigated the reactivity of three different metals by reacting the metals with each other's sulfates in solution.

This is the method that the student used.

  1. Place 1 g of the metal powder in a test tube.
  2. Add 10 cm3 of the metal sulfate solution.
  3. Shake slightly, wait 1 minute and observe.
  4. Repeat using the other metal sulfates and metals

The student tabulated her results as shown in Table 1 below. She placed a tick in the table if there was a reaction and a cross if there was no reaction.

Table 1

  Zinc Copper Magnesium
Magnesium sulfate      
Zinc sulfate      
Copper sulfate      


Give
one observation the student could make that shows there is a reaction between zinc and copper sulfate.

1d3 marks

Use the results shown in the table above to place the three metals in order of reactivity.

Most reactive     _________________________

                            _________________________

Least reactive    _________________________

1e1 mark

Suggest one reason why the student should not use potassium in this investigation.

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2a2 marks

A student investigated simple cells using the apparatus shown in Figure 1.

Figure 1

aqa-gcse-sq-4-1m-q2a-potassium-nitrate-cell

  • A positive voltage is measured if metal 2 is more reactive than metal 1.
  • A negative voltage is measured if metal 2 is less reactive than metal 1.
  • The magnitude of the voltage produced depends on the reactivity of the metals.
  • The bigger the difference in reactivity, the larger the voltage produced.

The student’s results are shown in Table 1 below:

Table 1

Metals

Chromium

Copper

Iron

Tin

Zinc

Chromium

0.0 V

       

Copper

1.3 V

0.0 V

     

Iron

0.6 V

Not measured

0.0 V

   

Tin

0.7 V

-0.3 V

0.4 V

0.0 V

 

Zinc

0.3 V

-1.2 V

-0.4 V

-0. 5V

0.0 V


The half equation for the reaction which occurs at the zinc electrode in the cell with copper and zinc electrodes is:

Zn → Zn2+ + 2e

State whether zinc is oxidised or reduced and explain why.

2b2 marks

Write down the half equation that occurs at the other electrode in the situation described in part (a).

2c2 marks

Look at the table above to determine which metal is the least reactive?

Give a reason for your answer.

Metal ____________________

Reason ______________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

2d3 marks

Predict the voltage that would be obtained for a simple cell with iron as metal 1 and copper as metal 2.

Explain your answer.

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3a2 marks

Table 1 provides information about some metals.

Table 1

Metal

Date of discovery

Main source

Main extraction method

Gold

Known to ancient civilisations

In the Earth's crust 

Physical separation

Zinc

1500

Zinc carbonate

Reduction by carbon

Sodium

1807

Sodium chloride

Electrolysis


Explain why gold is found in its unreacted form, as the metal itself in the Earth.

3b2 marks

The equation below shows one of the reactions in the extraction of zinc.

ZnO + C → Zn + CO

Explain why carbon is used to extract zinc.

3c3 marks

Sodium is one of the most abundant metals on Earth but was not extracted until 1807.

Explain, as fully as you can, why this is so.

3d3 marks

The reactivity series of metals contains two non-metals. 

State the names of these elements and give one reason why they are included.

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4a3 marks

This question is about the extraction and use of copper.

Most of the copper extracted globally is used in the production of electric circuits and wiring.

Figure 1 shows how impurities in the copper affect its electrical conductivity.

Figure 1

4-1-reactivity-of-metals-medium-q4a

Copper that is extracted by smelting is approximately 99% pure. 

This is then purified further to 99.9999% by electrolysis.

Use values from Figure 1 to explain why copper is purified to 99.9999%.

4b3 marks

Copper can be extracted from solutions of copper salts by the addition of iron. 

Use your knowledge of the reactivity series to explain why.

4c3 marks

Explain which species is reduced in the reaction between magnesium and copper (II) sulfate.

Mg + CuSO4 ⟶ Cu + MgSO4

Your answer should include the half equation for the reduction.

4d3 marks

Copper does not react with sulfuric acid but other metals such as iron or aluminium do. 

Explain this trend in terms of the reactivity series and the tendency to form a positive ion.

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5a2 marks

This question is about redox reactions.

Copper (II) oxide and hydrogen gas react to produce copper and water.

Write a balanced symbol equation for the reaction including state symbols.

__________ + __________ → __________ + __________

5b2 marks

Identify the chemical species being oxidised and the species being reduced.

5c3 marks

The balanced equation for the displacement of copper from copper (II) sulphate by zinc is shown:

CuSO4 (aq) + Zn (s) → ZnSO4 (aq) + Cu (s)

Write the overall ionic equation and both half equations for the reaction.

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