AQA GCSE Chemistry (8462), Higher tier · Chemical changes › Reactivity of metals
Practise Extraction of metals and reduction. 12 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Complete the sentence. Reduction is the .................... of oxygen.
loss
Tin is extracted by heating tin(IV) oxide, SnO2, with carbon. The products are tin and carbon dioxide. Write a balanced symbol equation for this reaction.
SnO2 + C → Sn + CO2
Tungsten is a metal used to make welding electrodes. Tungsten is less reactive than carbon. However, if tungsten oxide is heated with carbon, some of the tungsten produced reacts with the carbon to form tungsten carbide. Instead, tungsten is extracted by heating tungsten oxide with hydrogen at a high temperature: WO3 + 3H2 → W + 3H2O Name the substance that is oxidised.
hydrogen
A student heats a mixture of black copper(II) oxide powder and carbon powder strongly in a boiling tube. The tube is connected to a second tube containing limewater. Write a word equation for the reaction in the first tube.
copper oxide + carbon → copper + carbon dioxide
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Most metals are found in the Earth's crust as compounds. Chemical reactions are needed to extract the metals.
(a) Gold is found in the Earth as the metal itself. Explain why.[1]
(b) Which metal can be extracted by heating its oxide with carbon? Tick (✓) one box.[1]
Aluminium
Iron
Magnesium
Sodium
(c) Complete the sentence. Reduction is the .................... of oxygen.[1]
(d) Zinc is extracted by heating zinc oxide with carbon: zinc oxide + carbon → zinc + carbon monoxide Which substance is reduced in this reaction?[1]
Show the answer and mark scheme
(a)
gold is very unreactive (so it does not form compounds)
(b)Answer: Iron
(c)Answer: loss
loss / removal
(d)Answer: zinc oxide
zinc oxide
Question 2Medium6 marks
Part of the reactivity series is shown below, with the most reactive element first. potassium, sodium, calcium, magnesium, aluminium, carbon, zinc, iron, tin, copper
(a) Name two metals in the list that can be extracted by heating their oxides with carbon.[2]
(b) Explain why aluminium cannot be extracted by heating aluminium oxide with carbon.[1]
(c) Tin is extracted by heating tin(IV) oxide, SnO2, with carbon. The products are tin and carbon dioxide. Write a balanced symbol equation for this reaction.[1]
(d) Identify the substance that is oxidised in the extraction of tin. Give a reason for your answer.[2]
Show the answer and mark scheme
(a)
one from zinc / iron / tin / copper
a second, different metal from zinc / iron / tin / copper
(b)
aluminium is more reactive than carbon (so carbon cannot remove oxygen from aluminium oxide)
(c)Answer: SnO2 + C → Sn + CO2
SnO2 + C → Sn + CO2
(d)
carbon
it gains oxygen (to form carbon dioxide)
Question 3Hard6 marks
Tungsten is a metal used to make welding electrodes. Tungsten is less reactive than carbon. However, if tungsten oxide is heated with carbon, some of the tungsten produced reacts with the carbon to form tungsten carbide. Instead, tungsten is extracted by heating tungsten oxide with hydrogen at a high temperature: WO3 + 3H2 → W + 3H2O
(a) Explain why this reaction is a reduction of tungsten oxide.[1]
(b) Name the substance that is oxidised.[1]
(c) Suggest why hydrogen, rather than carbon, is used to extract tungsten.[1]
(d) Suggest one disadvantage of using hydrogen to extract tungsten.[1]
(e) Calculate the maximum mass of tungsten that can be extracted from 46.4 kg of tungsten oxide. Relative atomic masses (Ar): O = 16, W = 184[2]
Show the answer and mark scheme
(a)
tungsten oxide loses oxygen
(b)Answer: hydrogen
hydrogen
(c)
carbon would react with the tungsten / form tungsten carbide, so the tungsten would be impure
(d)
hydrogen is flammable / explosive (with air)
hydrogen has to be made first, which uses energy / is expensive
a high temperature is needed, so energy costs are high