Q1.
Alkanes are hydrocarbons found in crude oil.
(a)
(i)
Complete the sentence.
Hydrocarbons contain the elements ......................... and .........................
only.
(1)
(ii)
Ethane is an alkane with the formula C2H6
Draw a ring around the correct answer to complete the sentence.
CnHn
Alkanes are hydrocarbons with the general formula
CnH2n
CnH2n+2
(1)
(b)
Crude oil is separated into useful fractions by fractional distillation.
Describe and explain how crude oil is separated into fractions by fractional distillation.
Use the diagram to help you answer the question.
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(4)
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(c)
Dodecane (C12H26) from crude oil is cracked to produce ethene (C2H4).
(i)
Complete the equation for this reaction.
C12H26
2 C2H4 + ............................
(1)
(ii)
Give two conditions needed for cracking.
1 ............................................................................................................
2 ............................................................................................................
(2)
(Total 9 marks)
Q2.
This question is about compounds produced from crude oil.
The table below shows four of these compounds.
(a)
Compound
Melting point in °C
Boiling point in °C
methane (CH4)
−183
−164
ethene (C2H4)
−169
−104
decane (C10H22)
−30
+174
icosane (C20H42)
+37
+343
Tick (
) two correct statements about the four compounds.
Statement
Tick (
)
Methane has the lowest melting point and icosane has the
highest boiling point.
Ethene and methane are alkanes.
Methane and decane are gases at room temperature (20°C).
Decane and icosane are liquid at 100°C.
(2)
(b)
Petrol contains a mixture of compounds, including octane (C8H18).
Complete the word equation for the complete combustion of octane.
octane + oxygen → ........................................ + ........................................
(2)
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(c)
Most petrol used in cars contains about 5% ethanol (C2H5OH).
Ethanol can be produced from sugar cane.
(i)
Draw a ring around the correct answer to complete the sentence.
combustion.
The reaction to produce ethanol from sugar solution is
displacement.
fermentation.
(1)
(ii)
Some people say that increasing the production of ethanol from sugar cane will be
good for the environment.
Suggest two reasons why.
1 ............................................................................................................
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2 ............................................................................................................
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(2)
Page 3 of 10
(iii)
Other people say that increasing the production of ethanol from sugar cane will be
bad for the environment.
Suggest two reasons why.
1 ............................................................................................................
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2 ............................................................................................................
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...............................................................................................................
(2)
(Total 9 marks)
Q3.
Petrol is a hydrocarbon fuel.
(a)
Complete this sentence.
Hydrocarbons are compounds which are made from the elements ...........................
and ........................................ only.
(2)
(b)
This apparatus was used to study the combustion of a hydrocarbon fuel.
(i)
Name the substance which changed the anhydrous copper sulphate from white to
blue.
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(1)
Page 4 of 10
(ii)
Carbon dioxide is also produced when the hydrocarbon fuel is burned.
Name the solution, labelled X on the diagram, which tests for carbon dioxide.
...........................................................................................................................
(1)
(iii)
Complete this sentence.
Carbon dioxide turns solution X ..............................................................................
(1)
(c)
The graph shows how the concentration of carbon dioxide in the air has varied since the
year 1000.
(i)
Describe the changes in the concentration of carbon dioxide in the air since the
year 1000.
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(3)
(ii)
Suggest why the concentration of carbon dioxide in the air has changed since the
year 1800.
...........................................................................................................................
...........................................................................................................................
(1)
(Total 9 marks)
Page 5 of 10
Q4.
The structural formulae of two saturated hydrocarbons are shown below.
Describe two ways in which they will differ in their physical properties.
1 .................................................................................................................................
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2 .................................................................................................................................
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(Total 2 marks)
Page 6 of 10
M1.
(a)
(i)
hydrogen / H and carbon / C
answers can be in either order
if letters given, must be capital H
1
(ii)
CnH2n+2
1
(b)
(most) crude oil vaporises / evaporates or crude oil enters as a vapour
1
(vapour) cools as it rises up the tower / column or tower / column cooler at the top
or negative temperature gradient
1
the fractions have different boiling / condensation points / ranges
accept the larger the molecules, the higher the boiling point /
condensation point
1
so they will condense at different levels in the tower
allow will collect at different levels if condensation mentioned
allow will condense to give different fractions
if no other mark is gained allow 1 mark for mention of heating
1
(c)
(i)
C8H18
if one answer is given C8H18 is the only acceptable answer
credit any correct combination of alkanes and alkenes, eg C5H12
and C3H6
1
(ii)
hot / high temperature
accept any temperature in the range 300 − 900 °C
‘heat’ is insufficient
1
catalyst
accept a named catalyst − alumina or zeolites or aluminosilicates
or broken pot
ignore other named catalysts
allow (mixing with) steam as an alternative to second marking point
ignore pressure
1
[9]
M2.
(a)
Methane has the lowest melting point and icosane has the highest boiling point
1
Decane and icosane are liquid at 100°C
1
Page 7 of 10
(b)
water / H2O
either order
1
carbon dioxide / CO2
allow hydrogen oxide
1
(c)
(i)
fermentation
1
(ii)
any two from:
•
sugar cane / plants absorb carbon dioxide
ignore oxygen released
•
growing sugar cane / plants reduces global warming
allow ethanol from plants is carbon neutral
•
renewable resource / sustainable
accept conserves fossil fuels / petrol
2
(iii)
any two from:
•
destruction of habitats / forests (to grow sugar cane/crops)
•
fermentation releases carbon dioxide
•
production plants cause visual pollution
•
pollution from the transportation of sugar cane / Ethanol
•
growing sugar cane / plants uses a lot of land
2
[9]
M3.
(a)
hydrogen
accept correct symbols but not H2
1
carbon
1
(b)
(i)
water
accept H2O
1
(ii)
limewater / calcium hydroxide
accept Ca(OH)2
1
(iii)
milky / cloudy / chalky / white
1
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(c)
(i)
remains almost the same / increases then decreases slightly from
1000 to 1800
1
increases / rises after 1800
1
rapidly (owtte)
1
(ii)
increased burning of hydrocarbon / (fossil) fuels, etc. or
increased use of fuels
accept deforestation
accept (more) cars / lorries / planes etc.
accept power stations
do not accept just ‘factories’
1
[9]
M4.
B will have higher melting point
higher boiling point
be less volatile
be more viscous (allow less flammable)
any two for 1 mark each
[2]
Page 9 of 10
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