11.6 EXTRA EXAM QUESTIONS
General Principles of Extraction
1.
(a)
Iron can be obtained from its oxide, Fe2O3, by reaction with carbon, aluminium or
hydrogen. Write an equation for the reaction in each case.
Equation for reaction with carbon.
....................................................................................................................................
Equation for reaction with aluminium.
....................................................................................................................................
Equation for reaction with hydrogen.
....................................................................................................................................
(3)
(b)
State, with an explanation, which of the reducing agents used above is likely to lead to
(i)
the cheapest iron,
Reducing agent..................................................................................................
Explanation........................................................................................................
...........................................................................................................................
(ii)
the purest iron.
Reducing agent...................................................................................................
Explanation.........................................................................................................
............................................................................................................................
(4)
(Total 7 marks)
2.
By giving reagents and conditions, state three different methods of extracting metals
starting from their oxides. In each case, write an equation, or equations, to illustrate the
extraction of an appropriate metal.
Method 1
Reagent(s) ...................................................................................................................
Conditions ..................................................................................................................
Equation(s) .................................................................................................................
.....................................................................................................................................
Method 2
Reagent(s) ...................................................................................................................
Conditions ..................................................................................................................
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Equation(s) .................................................................................................................
.....................................................................................................................................
Method 3
Reagent(s) ...................................................................................................................
Conditions ..................................................................................................................
Equation(s) .................................................................................................................
.....................................................................................................................................
(9)
3.
Give two reasons why carbon is used in industry to reduce iron oxide.
Reason 1 ...........................................................................................................
Reason 2 ...........................................................................................................
4.
(a)
Write an equation, or two half-equations, to show the essential reactions occurring during
the extraction of the following from their oxides.
Equation(s) for iron.....................................................................................................
.....................................................................................................................................
Equation(s) for aluminium..........................................................................................
.....................................................................................................................................
(3)
(b)
Tungsten is prepared in a pure form by high temperature reduction of tungsten( VI) oxide
with hydrogen.
(i)
Construct an equation for this reaction.
.........................................................................................................................
(ii)
Suggest why carbon is not used as the reducing agent.
.........................................................................................................................
(iii)
Suggest one advantage (other than purity of the product) and one disadvantage of
using hydrogen as the reducing agent on an industrial scale.
Advantage........................................................................................................
.........................................................................................................................
Disadvantage...................................................................................................
.........................................................................................................................
(4)
(Total 7 marks)
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Extraction of Iron
5.
(a)
State two compounds formed during the extraction of iron in the blast furnace which lead to
environmental pollution. In each case identify the type of pollution caused.
Compound 1................................................................................................................
Pollution caused..........................................................................................................
Compound 2................................................................................................................
Pollution caused..........................................................................................................
(4)
(b)
Outline the essential chemistry of the process for converting crude iron into a carbon steel.
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
(2)
(Total 6 marks)
6.
(a)
Iron is extracted from the oxide Fe2O3 by reduction with carbon and carbon monoxide in
a Blast Furnace.
(i)
In the Blast Furnace, carbon monoxide is produced from carbon in a two-stage
process. Write equations to show these two stages.
Stage 1 ..............................................................................................................
Stage 2 ..............................................................................................................
(ii)
Write an equation for the reduction of Fe2O3 by carbon and an equation for the
reduction of Fe2O3 by carbon monoxide.
Equation for carbon .........................................................................................
Equation for carbon monoxide ........................................................................
(iii)
Limestone is added to the Blast Furnace to remove impurities present in the iron
ore. Identify the main impurity removed by limestone. Write an equation or
equations to show how limestone acts to remove this impurity
Impurity ............................................................................................................
Equation(s) .......................................................................................................
...........................................................................................................................
(b)
(7)
State the main impurity in iron obtained from the Blast Furnace. Explain how this
impurity is removed in the conversion of impure iron into steel.
Impurity ......................................................................................................................
Explanation .................................................................................................................
.....................................................................................................................................
(3)
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(c)
Identify a gas which is released from the Blast Furnace which leads to environmental
problems. State the environmental problem.
Gas ..............................................................................................................................
Environmental problem ..............................................................................................
(2)
(d)
Identify another gas which leads to environmental problems when sulphide ores are used
in the extraction of metals other than iron. State the environmental problem.
Gas ..............................................................................................................................
Environmental problem ..............................................................................................
(2)
(Total 14 marks)
7.
(a)
(i)
Write an equation for the reaction which is mainly responsible for the high
temperature in the Blast Furnace.
......................................................................................................................
(ii)
Write an equation for a reaction in which iron is formed from its oxide in the Blast
Furnace.
......................................................................................................................
(iii)
Iron from the Blast Furnace can contain sulphur. Write an equation to show how
this impurity is removed.
......................................................................................................................
(iv)
Iron from the Blast Furnace contains carbon. State how most of this carbon is
removed. Give one reason why this removal is necessary.
Removal of carbon........................................................................................
......................................................................................................................
Reason..........................................................................................................
......................................................................................................................
(6)
(Total 6 marks)
8.
(a)
Explain how the impurity silicon(IV) oxide is removed during the extraction of iron in the
Blast Furnace.
Discuss the chemical reactions by which impurities are removed from iron in the basic
oxygen converter.
(13)
(b)
Describe how scrap iron is recycled. Discuss the social and environmental benefits of this
recycling.
(6)
(Total 19 marks)
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Extraction of Aluminium
Indicate how the following conversion can be carried out.
9.
A12O3
Al
....................................................................................................................................
....................................................................................................................................
(2)
10.
Aluminium is not usually extracted by heating aluminium oxide with carbon, but carbon
does have a use in the extraction of aluminium from aluminium oxide. State how carbon is
used during the extraction process and write a half-equation showing how aluminium is
produced.
Use of carbon .........................................................................................................
Half-equation..........................................................................................................
(2)
Extraction of Titanium
11.
Indicate how the following conversion can be carried out.
TiO2
TiCl4
....................................................................................................................................
....................................................................................................................................
(2)
12. (a)
By giving the reagent(s), conditions and an equation, state how titanium is extracted from
titanium(IV) chloride.
Reagent(s) ...................................................................................................................
Conditions ...................................................................................................................
Equation ......................................................................................................................
(4)
(b)
(i)
State two reasons why titanium is expensive.
Reason 1 ...........................................................................................................
Reason 2 ...........................................................................................................
(ii)
Give two properties of titanium which make it useful despite its cost.
Property 1 .........................................................................................................
Property 2 .........................................................................................................
(4)
(Total 8 marks)
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13.
In this question, credit will be given for appropriate equations.
Describe the process by which titanium metal is extracted from titanium(IV) oxide.
Explain why this extraction process causes titanium to be an expensive metal.
(11)
Combination Questions
14.
Aluminium and titanium are extracted from their purified oxides by different methods.
(a)
Discuss, with the aid of chemical equations, the method used for each metal.
(10)
(b)
Explain why each method is chosen.
(4)
(c)
Explain why aluminium is recycled although aluminium oxide is in plentiful supply.
(3)
(Total 17 marks)
15.
Describe, by giving reagents, essential conditions and equations, how iron and titanium
are extracted industrially from their oxides.
(Total 9 marks)
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