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Reactivity series and metal extraction

Use the reactivity series to predict displacement reactions and explain how metals are extracted.

Start here

The key idea

Metals higher in the reactivity series react more vigorously.A more reactive metal displaces a less reactive one from a solution of its salt.Metals below carbon are extracted by reduction; those above by electrolysis.

Reactivity Series
KNaCaMgAlCZnFeCumore reactivecan displace lower metals

Use the labels to explain the scientific relationship shown.

Revision notes

The bit that matters

Keep the idea tight, then use the worked example to practise the exact exam wording.

1

The reactivity series

The reactivity series orders metals by their tendency to lose electrons and form positive ions.From most to least reactive: potassium, sodium, lithium, calcium, magnesium, aluminium, (carbon), zinc, iron, (hydrogen), copper, silver, gold, platinum.A metal higher in the series will displace a metal lower in the series from a solution of its salt.

2

Extraction of metals

How a metal is extracted depends on its position in the reactivity series.Metals below carbon (zinc, iron, tin, lead, copper) can be extracted by reduction with carbon or carbon monoxide.Metals above carbon (potassium, sodium, calcium, magnesium, aluminium) are too reactive to be reduced by carbon and must be extracted by electrolysis of their molten compounds.

3

The blast furnace

Iron is extracted in a blast furnace by reducing iron oxide with carbon (as coke).The key reactions are: C + O₂ → CO₂; CO₂ + C → 2CO; Fe₂O₃ + 3CO → 2Fe + 3CO₂.Limestone (CaCO₃) is added to remove acidic impurities as slag (calcium silicate).The molten iron sinks to the bottom of the furnace.

4

Recycling and sustainability

Extracting metals is energy-intensive and depletes finite ore resources.Recycling metals saves energy, conserves resources and reduces landfill waste.Copper can also be extracted from low-grade ores by bioleaching (using bacteria) or phytomining (using plants that absorb and concentrate copper), then by displacement or electrolysis.

Key terms

Definitions to learn

Reactivity series

A list of metals in order of decreasing reactivity with water and acids.

Displacement reaction

A reaction in which a more reactive element displaces a less reactive element from a compound.

Reduction

Gain of electrons (or removal of oxygen from a compound); used to extract metals from their oxides.

Oxidation

Loss of electrons (or addition of oxygen to a substance).

Ore

A rock that contains enough of a metal compound to make extraction economically worthwhile.

Phytomining

Extracting metals from low-grade ores using plants that absorb and concentrate metal ions in their biomass.

Worked example

Explain whether iron will displace copper from copper sulfate solution.

1

Check the reactivity series: iron is above copper.

2

A more reactive metal displaces a less reactive one.

3

Iron will displace copper: Fe + CuSO₄ → FeSO₄ + Cu.

4

Iron dissolves and copper metal deposits.

Final answer

Yes — iron displaces copper because iron is more reactive. The solution turns from blue to pale green.

Exam habit

For every reactivity prediction, state the positions of both metals in the series and explain which is more reactive before predicting the outcome.

Watch out

Do not say the most reactive metal always reacts fastest — reactivity refers to the ease of losing electrons, not reaction rate.

Examiner tips

How to score full marks

  • 1State the relative positions of BOTH metals in the reactivity series before predicting whether displacement occurs.
  • 2Metals above carbon in the reactivity series are extracted by ELECTROLYSIS (not reduction with carbon).
  • 3Describe displacement observations fully: colour change of solution AND appearance of metal deposit.
Practice questions

Try these yourself

Open each answer only after you have explained the full chemical process.

1State what is meant by a displacement reaction in terms of reactivity.[1 mark]
Mark scheme
  1. 1.Compare the reactivity of two metals.
A more reactive metal displaces a less reactive metal from a solution of its salt (1).
2Predict whether zinc will react with magnesium sulfate solution. Explain your reasoning.[3 marks]
Mark scheme
  1. 1.Compare positions in the reactivity series.
No (1) — zinc is less reactive than magnesium (1), so it cannot displace magnesium from its salt (1).
3Explain why gold is found as the native metal in the Earth's crust.[3 marks]
Mark scheme
  1. 1.Link low reactivity to not forming compounds.
Gold is very unreactive (1) and does not readily combine with other elements (1), so it remains as the uncombined metal (1).
4State why aluminium is extracted by electrolysis rather than reduction with carbon.[3 marks]
Mark scheme
  1. 1.Compare the positions of aluminium and carbon in the reactivity series.
Aluminium is more reactive than carbon (1), so carbon cannot reduce aluminium oxide (1); electrolysis must be used instead (1).
5Write a balanced equation for the reduction of iron oxide with carbon in a blast furnace.[2 marks]
Mark scheme
  1. 1.Identify the reactants and products.
2Fe₂O₃ + 3C → 4Fe + 3CO₂ (1) balanced (1).
6Explain why it is more expensive to extract aluminium than iron.[4 marks]
Mark scheme
  1. 1.Link to the extraction method used.
Aluminium is extracted by electrolysis (1), which requires a large amount of electrical energy (1); iron is extracted by reduction with carbon (1), which requires only the burning of coke and is less energy-intensive (1).
7Describe what you would observe when a piepiece of magnesium ribbon is added to blue copper sulfate solution.[3 marks]
Mark scheme
  1. 1.Describe the visual changes.
The blue colour of the solution fades / disappears (1); copper metal (orange/brown) deposits on the magnesium (1); the magnesium ribbon disappears/dissolves (1).
8Explain phytomining as a method for extracting copper from low-grade ore.[4 marks]
Mark scheme
  1. 1.Describe how plants are used in the process.
Plants absorb copper ions from the soil and concentrate them in their biomass (1); the plants are burnt (1); the ash is leached with acid to produce a copper-rich solution (1); copper is then extracted from the solution by displacement with scrap iron or by electrolysis (1).
Official exam-board sources
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