Q1.
The high demand for petrol (octane) can be met by breaking down longer hydrocarbons,
such as decane, by a process known as cracking.
(a)
Apart from heat, what is used to make the rate of this reaction faster?
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(1)
(b)
Octane is a hydrocarbon.
(i)
What does hydrocarbon mean?
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(1)
(ii)
Give the molecular formula of octane.
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(1)
(c)
The hydrocarbon X is used to make poly(ethene).
(i)
What is the name of X?
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(1)
(ii)
What is the name of the process in which X is changed into poly(ethene)?
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(1)
(Total 5 marks)
Page 1 of 16
Q2.
(a)
The hydrocarbon C16H34 was heated strongly in the absence of air.
This is one of the reactions which took place:
C16H34
C6H14
+
C6H12
+
2C2H4
This type of reaction is carried out because there is a greater demand for the products
than for the original hydrocarbon.
Suggest two reasons for this.
1 .................................................................................................................................
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2 .................................................................................................................................
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(2)
(b)
A molecule of the compound methane, CH4, can be shown like this:
Draw a molecule of the compound ethene, C2H4.
(2)
(c)
Small molecules of substances called monomers can be joined together in polymerisation,
eg. ethene poly
(ethene).
(i)
Complete the equation below to show formation of the polymer from the
monomer propene.
(1)
Page 2 of 16
(ii)
Suggest the name of the polymer formed.
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(1)
(Total 6 marks)
Q3.
In this question you will be assessed on using good English, organising information clearly
and using specialist terms where appropriate.
There are millions of plastic bags in use. After use most of these plastic bags are buried in
landfill sites. The amount sent to landfill could be reduced if the plastic bags:
•
could be reused
•
could be recycled by melting and making them into new plastic products
•
could be burned to release energy.
Use the information above and your knowledge and understanding to give the positive and
negative environmental impacts of using these methods to reduce the amount of plastic bags
sent to landfill.
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(Total 6 marks)
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Q4.
Most plastic bags are made from poly(ethene).
Poly(ethene) is a polymer made from ethene.
Ethene is made by cracking saturated hydrocarbons from crude oil.
(a)
Use words from the box to complete the sentences about cracking.
alkanes
alkenes
catalyst
fuel
gas
Cracking involves heating the .......................................... to make a vapour.
The vapour is either passed over a hot ............................................... or mixed
with steam and heated to a very high temperature so that thermal decomposition
reactions happen.
(2)
(b)
Poly(ethene) molecules are made from ethene molecules by a polymerisation reaction.
Describe what happens in a polymerisation reaction.
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(2)
(c)
In this question you will be assessed on using good English, organising information clearly
and using specialist terms where apropriate.
There are millions of plastic bags in use. After use most of these plastic bags are buried in
landfill sites. The amount sent to landfill could be reduced if the plastic bags:
•
could be reused
•
could be recycled by melting and making into new plastic products
•
could be burned to release energy
Page 4 of 16
Use the information above and your knowledge and understanding to give the positive and
negative environmental impacts of using these methods to reduce the amount of plastic
bags sent to landfill.
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(6)
(Total 10 marks)
Q5.
Water sold in plastic bottles has a high ‘carbon cost’.
The ‘carbon cost’ depends on the amount of carbon dioxide emitted in making and transporting
the product.
The more carbon dioxide emitted, the higher the ‘carbon cost’.
(a)
Plastic water bottles are made from a polymer.
The polymer is made from ethene.
Ethene is made by cracking hydrocarbons.
(i)
Name the polymer made from ethene.
...........................................................................................................................
(1)
Page 5 of 16
(ii)
Ethene can be made by cracking the hydrocarbon pentane, C5H12.
C5H12 → C2H4
+
C3H8
Explain why there is a ‘carbon cost’ for the process of cracking a hydrocarbon.
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(2)
(b)
The diagram shows information about water sold in plastic bottles in the UK.
The diagram also shows the average distances that water and plastic bottles are
transported.
Suggest how the high ‘carbon cost’ of water sold in plastic bottles could be reduced.
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(3)
(Total 6 marks)
Page 6 of 16
Q6.
The diagram shows an apparatus that can be used to carry out cracking reactions in a
laboratory.
(a)
Why is aluminium oxide or broken porcelain used?
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.....................................................................................................................................
(1)
(b)
Paraffin contains decane. The cracking of decane can be represented by the equation
below. A decane molecule is split into two smaller molecules.
Complete the equation by adding the formula of the other product.
C10H22 (l) →.................... (l) + C2H4 (g)
decane
(1)
(c)
Would you expect C2H4 molecules to collect at position A or B shown on the diagram?
Position ............................
Explain your answer.
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(1)
Page 7 of 16
(d)
Cracking reactions involve thermal decomposition.
What is meant by thermal decomposition?
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(2)
(e)
Explain, as fully as you can, why cracking is used in the oil industry.
To gain full marks in this question you should write your ideas in good English. Put them
into a sensible order and use the correct scientific words.
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(3)
(f)
The cracking reaction produces a mixture of products. The mixture contains hydrocarbons
with different boiling points.
Suggest a method of separating this mixture.
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(1)
(Total 9 marks)
Page 8 of 16
M1.
(a)
catalyst
1
(b)
(i)
made up of only carbon and hydrogen
1
(ii)
C8H18
1
(c)
(i)
ethene
1
(ii)
polymerisation
1
[5]
M2.
(a) smaller, more useful molecules more reactive (molecules)/(molecules) used to make
plastics more easily ignited/better fuels produces unsaturated compounds/alkenes
any two for 1 mark each
2
(b)
gains 1 mark
2
but
gains 2 marks
(c)
(i)
for 1 mark
1
Page 9 of 16
(ii)
poly(propene)
(N.B. brackets not required; allow “polypropylene”)
for 1 mark
1
[6]
M3.
Marks awarded for this answer will be determined by the Quality
of Written Communication (QWC) as well as the standard of the
scientific response.
No relevant content.
0 marks
There is a brief description of a positive and a negative environmental
impact involved with one or more methods used to reduce the
amount of plastic bags sent to landfill.
Level 1 (1–2 marks)
There is some description of both positive and negative
environmental impacts involved with at least 2 methods used
to reduce the amount of plastic bags sent to landfill.
Level 2 (3–4 marks)
There is a clear, balanced and detailed description of both a
positive and a negative environmental impact of using each
of the 3 methods used to reduce the amount of plastic bags
sent to landfill.
Level 3 (5–6 marks)
examples of the points made in the response
Reuse:
Reuse means less bags used so:
Positive environmental impact
•
Saves raw materials/crude oil
•
Saves energy
•
Cuts down on CO2 emissions
•
Less global warming
Negative environmental impact
•
Could cause litter
•
Could still be sent to landfill
Page 10 of 16
Recycle:
Bags can be recycled so:
Positive environmental impact
•
Used to make new plastic bags / objects
•
Saves raw materials / crude oil
•
Saves energy compared to producing plastic bags from crude oil
•
Cuts down on CO2 emissions
•
Less global warming
Negative environmental impact
•
Collection point sites cause an eyesore / litter problem
•
Transportation to recycling plant releases carbon dioxide / causes global warming
Burn:
Bags can be burned so:
Positive environmental impact
•
Could provide energy for heating buildings
•
Could provide energy for generating electricity
Negative environmental impact
•
Increases CO2 emissions
•
Increases global warming
•
Could release toxic gases
•
Does not conserve raw materials / crude oil
[6]
M4.
(a)
alkanes
1
catalyst
1
substances must be in the order shown
(b)
many (ethenes/monomers)
1
bond/join together
1
allow ethenes / monomers bond / join together to form very large
molecules for 2 marks
Page 11 of 16
(c)
Marks awarded for this answer will be determined by the
Quality of Written Communication (QWC) as well as the
standard of the scientific response.
No relevant content.
0 marks
There is a brief description of a positive and a negative
environmental impact involved with one or more methods
used to reduce the amount of plastic bags sent to landfill.
Level 1 (1–2 marks)
There is some description of both positive and negative
environmental impacts involved with at least 2 methods
used to reduce the amount of plastic bags sent to landfill.
Level 2 (3–4 marks)
There is a clear, balanced and detailed description of both
a positive and a negative environmental impact of using
each of the 3 methods used to reduce the amount of plastic
bags sent to landfill.
Level 3 (5–6 marks)
examples of the chemistry points made in the response
reuse:
reuse means less bags used so:
positive environmental impact
•
saves raw materials / crude oil
•
saves energy
•
cuts down on CO2 emissions
•
less global warming
negative environmental impact
•
could cause litter
•
could still be sent to landfill
Page 12 of 16
recycle:
bags bought can be recycled so:
positive environmental impact
•
used to make new plastic bags / objects
•
saves raw materials / crude oil
•
saves energy compared to producing plastic bags
from crude oil
•
cuts down on CO2 emissions
•
less global warming
negative environmental impact
•
collection point sites cause an eyesore / litter problem
•
transportation to recycling plant releases carbon
dioxide / causes global warming
burn:
bags can be burned so:
positive environmental impact
•
could provide energy for heating buildings
•
could provide energy for generating electricity
negative environmental impact
•
increases CO2 emissions
•
increases global warming
•
could release toxic gases
does not conserve raw materials / crude oil
[10]
M5.
(a)
(i)
polyethene / poly(ethene)
accept polythene / polyethylene
1
(ii)
needs heat / energy / high temperature / fuel (for cracking)
ignore other processes
1
produces carbon dioxide / CO2
ignore use of CO2 or ‘produces carbon’
1
Page 13 of 16
(b)
any three from:
•
use water from local sources or water from close to home
•
recycle bottles in the UK / close to home
accept do not recycle in other countries / Asia
•
(reduction in distance travelled) would reduce CO2 emitted by transport
accept use of transport with low / no carbon dioxide emissions
•
use tap water
•
use glass bottles / waxed cartons / metal bottles
do not accept ‘do not use plastic bottles’ without an alternative
material
•
do not put in landfill or recycle more
•
reuse / refill plastic bottles
•
tax imported water / plastic bottles (to offset carbon cost)
•
make more / all plastic bottles in UK
answers must be about the reduction of carbon cost
3
[6]
M6.
(a)
catalyst or speeds up the reaction (owtte)
accept lowers activation energy not just helps reaction to take
place
ignore increased surface area
1
(b)
C8H18
allow H18C8
must be upper case
do not accept powers
1
(c)
B
because it is a gas or because it has small molecules or because they are small
position and reason for mark
allow it has a lower / very low boiling point than A
ignore references to solubility
accept does not condense
do not accept light molecules or bubbles into B
do not accept it is small
1
(d)
breakdown of a substance (owtte)
do not accept decompose unqualified
1
by the action of heat (owtte)
1
Page 14 of 16
(e)
Quality of written communication
if the written communication makes sense and it is in context then
award Q mark
Q Q
1
large to small molecules or scientific word that implies smaller,
e.g. alkene / ethane / petrol
any name or formula of alkane / alkene smaller than decane
1
either advantages of smaller molecules or disadvantages of larger molecules
e.g. hydrocarbons with large molecules are limited in their usefulness
or converse for smaller molecules
1
large hydrocarbon molecules do not ignite easily / do not flow easily /
are not very volatile
or converse for smaller molecules
more large hydrocarbon molecules are produced than are needed
or converse for smaller molecules
smaller molecules are useful as fuels
alkenes / products can be used to make polymers
(f)
(fractional) distillation
accept fractionation
accept good description
do not accept just diagram
1
[9]
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