Q1.
The table shows how much carbon dioxide is produced when you transfer the same amount
of energy by burning coal, gas and oil.
(a)
Use the information from the table to complete the bar-chart.
(3)
(b)
The second bar-chart shows how much sulphur dioxide is produced by burning the same
three fuels.
Compare the amount of sulphur produced by burning gas with the amount produced by
burning coal.
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(2)
(c)
(i)
Coal and oil produce carbon dioxide and sulphur dioxide when they burn.
What elements must they contain?
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(2)
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(ii)
Burning fuels also produce nitrogen oxides, even though the fuels contain no
nitrogen. Explain why this happens.
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(2)
(Total 9 marks)
Q2.
Crude oil is obtained by drilling into the Earth’s crust. The diagram shows a section through
the Earth’s crust to show how this is done.
(a)
Crude oil contains many hydrocarbons. Which elements do hydrocarbons contain?
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(1)
(b)
The crude oil is separated by fractional distillation. The diagram shows a column used
for this.
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(i)
Explain, as fully as you can, how fractional distillation works.
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(3)
(ii)
Naphtha burns more easily than diesel oil. Explain why.
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(1)
(iii)
Naphtha contains a saturated hydrocarbon with the formula C7H16 .
Draw the structural formula of this compound.
(2)
(Total 7 marks)
Q3.
Known crude oil reserves are being used up rapidly. Crude oil is used to produce many
useful fuels, such as petrol. One way to conserve crude oil reserves would be to increase the
production of bio-fuels.
(a)
Ethanol can be produced for use as a bio-fuel. Cars can be powered by ethanol or
ethanol–petrol mixtures.
Sugar cane can be fermented to give a mixture of water (boiling point 100 °C) and ethanol
(boiling point 78 °C).
(i)
How can ethanol be separated from water?
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(1)
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(ii)
Ethanol, C2H5OH, burns to release heat energy.
Complete the balanced symbol equation by writing in the formulae of the two
products.
C2H5OH
+
3O2
2.........
+
3.........
(2)
(b)
The cost of producing a bio-fuel, such as ethanol, by fermentation, is at least three times
higher than the production cost of petrol. It costs less to produce ethanol from alkanes. In
the production, the vapour of an alkane is passed over a hot catalyst.
Ethene is then converted into ethanol.
(i)
What has happened to the hexane to produce ethene?
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(1)
(ii)
Complete the structural formula for ethene, C2H4.
C
C
(1)
(iii)
Name the compound that is added to ethene to produce ethanol, C2H5OH.
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(1)
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(c)
As explained in parts (a) and (b), ethanol can be made using either sugar or alkanes as the
starting material.
Evaluate the advantages and disadvantages of using these two starting materials to
produce ethanol.
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(4)
(Total 10 marks)
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M1.
(a)
each bar correct height_ (2 bars) to less than
1 mark for each
½ square
both bars correctly labelled (in relation to size of bars)
for 1 mark
3
(b)
less
gains 1 mark
but a lot less / much less / 18 times less or more if referring to coal
gains 2 marks
2
(c)
(i)
carbon
sulphur
for 1 mark each
2
(ii)
ideas that
•
at high temperatures, (produced when fuels burn)
•
nitrogen and oxygen from atmosphere combine / react
for 1 mark each
2
[9]
M2.
(a)
hydrogen and carbon
for 1 mark
1
(b)
(i)
the oil is evaporated / boiled / liquid converted to gas / vaporised
oil is condensed/changed back to liquid/cooled below boiling point (not just cooled)
liquids of different boiling points condense at different levels /
fractions with lower boiling points form near the top /
boiling point linked to chain length or Mr
each for 1 mark
3
(ii)
Assume they mean naphtha unless they say otherwise.
smaller molecules
/contains less atoms
/lower boiling point
/more volatile
/less bonds to break
/lower activation energy
If the answer is given the opposite way around then diesel must
be specified.
any one for 1 mark
1
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(iii)
correct number of atoms = 1
correct number of bonds (attached to correct atoms) = 1
Accept diagrams which show electrons correctly.
CH3CH2CH2CH2CH2CH2CH3 = 1
for 2 marks
2
[7]
M3.
(a)
(i)
by (fractional) distillation
accept a description of the distillation process (heat and how
separation works) eg heat and condense
accept boil / vapourise etc for heat
or
fractionation
1
(ii)
CO2
note the order of these products must be correct
1
H2O
wrong way round = 1 mark
1
(b)
(i)
(hexane) has been broken down (into smaller hydrocarbons / molecules)
1
accept (thermal) decomposition / cracked / split / broken up owtte
(ii)
H
H
│ │
C
= C
│
│
H
H
accept CH2 = CH2
1
(iii)
water / hydrogen oxide / steam
accept H2O
1
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(c)
candidates must include both sugar cane and crude oil in their evaluation
and both an advantage and a disadvantage to gain full marks.
if they do not then the maximum mark is three
any four from:
advantages of using sugar
•
country has no wealth to buy (large quantities of) crude oil
not ‘expensive’ alone
•
country has limited technological development
or
underdeveloped / third world country
•
able / suitable climate to grow sugar cane
•
enough land to grow sugar cane / land cannot be used to grow food / deforestation
•
sugar is a renewable source
or
crude oil is a non-renewable resource / finite resource / limited resources
•
CO2 / carbon neutral
advantages of using alkanes:
•
economic costs are low
•
continuous process
•
country has large oil resources
•
country has oil refineries / cracking plants
•
very pure product
•
faster process
4
[10]
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