1.
Aluminium occurs as bauxite, which contains aluminium oxide with impurities mainly of
iron(III) oxide and silica.
(a)
Outline how bauxite is processed to give pure aluminium oxide, showing clearly the
chemical basis for the method.
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Aluminium is produced by electrolysis of purified aluminium oxide. State briefly the
necessary conditions, sketch and label the cell used. Give the reaction at each electrode.
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(b)
(5)
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(c)
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(5)
Electrolysis is very expensive. Why is it used for aluminium production but not for iron?
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NT Exampro
(2)
1
(d)
(i)
Sketch the structure of aluminium chloride, which has a molar mass of
267 g mol–1 in the vapour state, to show the bonding present.
[You are not required to show the shape of this molecule.]
(ii)
Why does aluminium chloride adopt this structure?
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Aluminium occurs as bauxite, which contains aluminium oxide with impurities mainly of
iron(III) oxide and silica.
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2.
(3)
(Total 15 marks)
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Outline how bauxite is processed to give pure aluminium oxide, showing clearly the chemical
basis for the method.
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(5)
NT Exampro
2
3.
Aluminium is produced by electrolysis of purified aluminium oxide. State briefly the necessary
conditions, sketch and label the cell used. Give the reaction at each electrode.
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4.
(5)
Sodium and sodium hydroxide are both manufactured by electrolytic processes.
Name the electrolyte used in the manufacture of:
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(a)
sodium hydroxide: ....................................................................................................
(i)
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(b)
(1)
What is produced at the anode during the manufacture of sodium hydroxide?
Write an equation for its formation.
Product: ............................................................................................................
Equation: ..........................................................................................................
What other gaseous product might be given off at the anode under other conditions?
Write an equation for its formation.
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(ii)
Product: ............................................................................................................
(5)
Suggest a reason why the product in (b)(i) is formed in the industrial process rather than
that in (b)(ii).
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(c)
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Equation: ..........................................................................................................
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(3)
(Total 9 marks)
NT Exampro
3
5.
(a)
Electrolysis of brine under different conditions gives sodium chlorate(I); in this case the
sodium hydroxide and chlorine are allowed to mix at room temperature.
(i)
Give the ionic equation for the reaction of chlorine with cold dilute aqueous sodium
hydroxide.
..........................................................................................................................
(1)
(ii)
If the solution of sodium chlorate(I) is heated, the chlorate(I) ion disproportionates.
Write the ionic equation for the reaction, and use it to explain the meaning of
disproportionation.
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Give one use for
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(b)
(3)
chlorine: …................................................................................................................
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(c)
(1)
Suggest how using a solution of sodium chlorate(I), or otherwise, you could distinguish
between separate aqueous solutions of potassium bromide and potassium iodide.
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Electrolysis of brine under different conditions gives sodium chlorate(I); in this case the sodium
hydroxide and chlorine are allowed to mix at room temperature.
(a)
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6.
(4)
(Total 9 marks)
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Give the ionic equation for the reaction of chlorine with cold dilute aqueous sodium
hydroxide.
.......................................……….................................................................................
(1)
NT Exampro
4
(b)
If the solution of sodium chlorate(I) is heated, the chlorate(I) ion disproprortionates.
Write the ionic equation for the reaction, and use it to explain the meaning of
disproportionation.
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(3)
(Total 4 marks)
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Consider the following list of equations which represent reactions. The letter E stands for
any particular element.
Equation 1
E(1)
→ E (g)
Equation 2
E(g)
→ E+(g) + e–
Equation 3
E(g) + e–
→ E–(g)
Equation 4
E+(g)
→ E2+(g) + e–
Equation 5
2E2+(aq)
→ E+(aq) + E3+(aq)
Equation 6
E(s)
→ E+(aq) + e–
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(a)
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7.
From the list write down the number of the equation which best represents the changes specified
in (i) to (viii) below. (There may be more than one answer in each case and equations may be
used more than once).
The first ionisation enthalpy.
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(i)
……..………………………………………………………………………….
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(ii)
(1)
The first electron affinity.
(iii)
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……..………………………………………………………………………….
(1)
The production of the molecular ion beam in a mass spectrometer.
……..………………………………………………………………………….
(1)
NT Exampro
5
(iv)
Oxidation.
……..………………………………………………………………………….
(1)
(v)
Typical behaviour of a metal.
……..………………………………………………………………………….
(1)
(vi)
An example of disproportionation.
……..………………………………………………………………………….
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(1)
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(vii) The process responsible for metallic bonding in solid metals.
……..………………………………………………………………………….
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(viii) A change of state.
(1)
……..………………………………………………………………………….
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(b)
(1)
Write balanced equations for the following chemical changes. You may ignore state
symbols.
(i)
The reaction of sodium metal with water.
……..………………………………………………………………………….
The reaction of calcium oxide with water.
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(ii)
(1)
……..………………………………………………………………………….
The effect of heat on solid magnesium carbonate.
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(iii)
(1)
……..………………………………………………………………………….
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(iv)
(1)
The reaction of chlorine gas with aqueous potassium bromide solution.
……..………………………………………………………………………….
(v)
(1)
The electrolysis of aqueous sodium chloride solution (brine).
……..………………………………………………………………………….
(1)
(Total 13 marks)
NT Exampro
6
8.
(a)
During the manufacture of sulphuric acid in the Contact Process sulphur dioxide reacts
with oxygen, in a reversible reaction, to form sulphur trioxide.
(i)
Write an equation to show the reaction between sulphur dioxide and oxygen.
..........................................................................................................................
(1)
(ii)
Give the name of the catalyst, and the values of temperature and pressure used.
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(iii)
Give one large scale use of sulphuric acid.
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(3)
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Aluminium is manufactured by electrolysis of a solution of aluminium oxide in molten
cryolite.
(i)
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(b)
(1)
Name the ore most commonly used in the extraction of aluminium.
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(ii)
(1)
Complete and balance the half equations below, to show the reactions occurring at
the electrodes during the extraction of aluminium.
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Al3+ + .......... → Al
(2)
From what material are the electrodes used in aluminium extraction made?
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(iii)
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.......... O2– → .......... O2 + ..........
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(iv)
(1)
State the major cost to the manufacturer during the extraction of aluminium.
..........................................................................................................................
(1)
NT Exampro
7
(v)
Give two reasons why aluminium is commonly recycled.
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(2)
(vi)
Give one large scale use of aluminium.
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9.
(a)
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(1)
(Total 13 marks)
Chlorine and sodium hydroxide are produced by electrolysis in a membrane cell.
(i)
What electrolyte is used?
(1)
State the gaseous product at the electrodes.
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(ii)
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………….……………….……………………………………………………..
Anode ………………………………………………………………………….
Cathode ………………………………………………………………………..
(iii)
(2)
Write the chemical equation for the overall reaction that occurs in the membrane
cell. There is no need to give state symbols.
(2)
Give one piece of everyday evidence that the reaction written in (iii) cannot occur
without electrolysis.
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(iv)
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………….……………….……………………………………………………..
………….……………….……………………………………………………..
(v)
(1)
State the purpose of the membrane in the electrolytic cell.
………….……………….……………………………………………………..
………….……………….……………………………………………………..
(1)
NT Exampro
8
(b)
Sodium chlorate(I) is made by allowing chlorine to react with sodium hydroxide at
room temperature.
(i)
Write the ionic equation for the reaction between sodium hydroxide and chlorine,
including state symbols.
………….……………….……………………………………………………..
(3)
(ii)
State why the reaction in (i) is a redox reaction.
………….……………….……………………………………………………..
(iii)
State one large-scale use of sodium chlorate(I).
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(1)
Aluminium is obtained from the ore bauxite.
(a)
The first stage is the purification of the ore.
(i)
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10.
(1)
(Total 12 marks)
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State the formula of the aluminium compound present in bauxite.
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(ii)
(1)
Identify the two major impurities in bauxite.
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w.
Explain, in terms of the properties of the substances in bauxite, why the addition of
10% sodium hydroxide solution is used to separate the aluminium compound from
the impurities in the bauxite.
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(iii)
(2)
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(3)
NT Exampro
9
(b)
The final stage is electrolysis.
(i)
State the name of the material used as the cathode.
......................................................................................................................
(1)
(ii)
Write the ionic equation for the reaction that takes place at the cathode.
......................................................................................................................
(1)
(iii)
Explain why the anode has to be replaced at regular intervals.
(2)
(Total 10 mark)
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NT Exampro
10