WORKSHEET TOPIC: Extraction of Aluminum
1 Which gases are all present at the positive electrode during the manufacture of aluminium?
A CO, H2, CO2 B O2, CO, CO2
C CO, SO2, H2O D SO2, H2, O2
2 An alloy of aluminium is used in the construction of aircraft. Why is pure aluminium never used?
A Pure aluminium cannot be manufactured.
B Pure aluminium conducts electricity.
C Pure aluminium is less dense than its alloys.
D Pure aluminium is too malleable.
3 The diagram shows apparatus that can be used to extract aluminium.
What are J, K and L?
J L
A negative aluminium oxide aluminium
electrode + cryolit
B negative cryolite aluminium oxide
electrode
C positive aluminium oxide cryolite
electrode
D positive aluminium oxide aluminium
electrode + cryolit
4 In the electrolysis of molten aluminium oxide for the extraction of aluminium, the following three
reactions take place.
1 Al 3+ + 3e– → Al
2 2O2– → O2 + 4e–
3 C + O2 → CO2
Which reactions take place at the positive electrode?
A 1 only B 2 only C 1 and 3 only D 2 and 3 only
5 Aluminium is manufactured by the electrolysis of molten aluminium oxide. Which gas is not formed
during this process?
A carbon dioxide B carbon monoxide
C oxygen D sulfur dioxide
6 Which gases are formed during the production of aluminium by electrolysis of molten aluminium
oxide?
A carbon dioxide, carbon monoxide, oxygen
B carbon dioxide, carbon monoxide, sulfur dioxide
C carbon dioxide, oxygen, sulfur dioxide
D carbon monoxide, oxygen, sulfur dioxide
7 Which statement about the material used for aircraft bodies is correct? Aircraft bodies are made
from
A an aluminium alloy because pure aluminium is too soft.
B pure aluminium because of its high melting point.
C pure aluminium because of its low density.
D pure aluminium because of its resistance to corrosion.
8 Zinc and aluminium both react with dilute hydrochloric acid. Why does zinc react more quickly than
aluminium?
A Aluminium is lower than hydrogen in the B Aluminium has an oxide coating.
reactivity series
C Zinc is an amphoteric element. D Zinc is a transition metal.
9 In the electrolysis of aluminium oxide to extract pure aluminium a compound called cryolite is first
added to the oxide. What is the reason for adding the cryolite?
A to reduce the corrosion of the carbon electrodes by oxygen
B to reduce energy costs
C to enable the aluminium ions and oxygen ions to move to the electrodes
D to prevent the aluminium formed from being oxidised back to aluminium oxide
10 The diagram shows the electrolytic production of aluminium.
waste gases
carbon
anodes
cathode
(positive)
(negative)
What are the products at the electrodes?
negative electrode positive electrode
A solid aluminium hydrogen
B solid aluminium oxygen
C liquid aluminium hydrogen
D liquid aluminium oxygen
11 Aluminium is used to make saucepans because of its apparent lack of reactivity. Which property of
aluminium explains its unreactivity?
A It has a high electrical conductivity. B It has a low density.
C It has a surface layer of oxide. D It is in Group III of the Periodic Table.
12 Which statement about the extraction of aluminium from aluminium oxide is correct?
A Aluminium is extracted by heating its oxide with carbon.
B Aluminium is extracted using electrolysis and is collected at the anode (positive electrode).
C Aluminium is extracted using platinum electrodes and direct current.
D Molten cryolite is used as a solvent for aluminium oxide.
13 From your knowledge of the manufacture of both aluminium and iron, what is the order of
chemical reactivity of aluminium, carbon and iron towards oxygen?
14 The diagram shows the electrolytic production of aluminium.
waste gases
carbon
anodes
cathode
(+ve)
(-ve)
What is the physical state of the aluminium oxide and aluminium during this process?
aluminium oxide aluminium
A liquid liquid
B liquid solid
C solid liquid
D solid solid
15 Why does aluminium have an apparent lack of reactivity?
A Aluminium has a coating of aluminium oxide, preventing further reaction.
B Aluminium has a giant molecular structure that is too hard to break.
C Aluminium is low in the reactivity series.
D The activation energy for the reaction of aluminium with other elements is too high.
A1. (a) In the production of aluminium, sodium hydroxide is used to separate aluminium
oxide from the impurities in the bauxite ore. The main impurity in the ore is
iron(III) oxide.
Aluminium oxide is an amphoteric oxide whilst iron(III) oxide is a basic oxide.
Suggest how these two oxides can be separated by the addition of aqueous
sodium hydroxide. [2]
(b) Aluminium is extracted by the electrolysis of a mixture of molten aluminium
oxide and cryolite. What is the function of the cryolite? [1]
(c) Acidic foods can be safely packed in aluminium containers.
Explain why the acid in the food does not attack the aluminium, despite the fact
that aluminium is a reactive metal. [2]
(d) Explain why aluminium will not corrode in the presence of oxygen and water. [1]
(e) State a use of aluminium and explain why this metal is particularly suited for the
stated use. [2]
(f) (i) Explain why aluminium appears to be unreactive. [2]
(ii) Explain why aluminium is used in the manufacture of aircraft. [1]
A2. (a) What properties of aluminium make it useful for
(i) making aircraft,
(ii) making electricity cables. [2]
(b) (i) Explain why aluminium does not react with aqueous copper(II) sulfate. [2]
(ii) When a few drops of aqueous sodium chloride are added to a mixture of
aluminium and aqueous copper(II) sulfate, a vigorous reaction occurs.
copper(II) sulfate + aluminium → aluminium sulfate + copper
What type of reaction is this? [1]
(c) Aluminium is extracted by the electrolysis of molten aluminium oxide
dissolved in cryolite. Construct the equation for the reaction at
(i) the anode (positive electrode), [1]
(ii) the cathode (negative electrode). [1]
