Grade 11 org. ques, polymerisation

Please Do Questions 5-8 and submit response by Sunday.
POLYMERIZATION
1. The diagram shows the structural formula for styrene. Styrene is a monomer that can
be made into a polymer.
(a) (i) Give evidence from the diagram that shows styrene is unsaturated. [1 mark]
Answer: Contains a double bond. [1]
(a) (ii) Complete the diagram to show the product in the equation. [2 marks]
Brackets correct [1] ’n’ in correct place [1]
(a) (iii) State the type of reaction involved in (a) (ii)
Answer: Addition Polymerization
(a) (iv) Styrene is produced from cracking long chain hydrocarbons. The products of cracking
include alkanes and unsaturated hydrocarbons called alkenes.
Alkenes can be made into polymers.
What is the general formula for an alkene molecule? [1 mark]
Answer: CnH2n [1]
(a) (v) One example of a polymer is polythene. Polythene is made into useful objects including
plastic bags.
Disposal of objects made from polystyrene can cause environmental problems.

Explain why. [3 marks]
ANSWER
 Polystyrene does not decompose. [1]
 Burning it can cause pollution. [1]
 If thrown in landfill it takes up space. [1]
(Total 7 marks)
Source: my-GCSEscience.com
Fractional Distillation
2. Crude oil is a mixture of hydrocarbons which can be separated into fractions.
(a) (i) What is a mixture? [2 marks]
Answer: Two or more elements or compounds [1] Not chemically combined or joined together
[1]
(a) (ii) What is a hydrocarbon? [2 marks]
Answer: A compound or molecule made up of hydrogen [1] AND and carbon only. [1]
1 (b) The table below gives some information on the hydrocarbon fractions found in crude oil.
Fraction Boiling Point % Crude Oil Carbon Chain
Length
Demand
Naptha 125 10 5 to 10 high
Kerosene 160 15 10 to 15 high
Diesel 250 20 15 to 20 medium
Fuel Oil 300 45 30 to 70 low
(b) (i) Naphtha has a lower boiling point than diesel.
Explain why. [2 marks]
Answer:
-Naptha (or it) contains short or shorter chains/hydrocarbons or smaller molecules or
contains fewer carbons. [1]
-Naptha (or it) has weaker / smaller intermolecular forces or smaller forces between the
molecules. [1]
(b) (ii) Kerosene is more expensive than fuel oil.
Suggest reasons why. [2 marks]

-Kerosene (or it) is in higher or high demand. [1]
-It is in short supply. [1]
(Total 8 marks)
The Alkanes
3. Crude oil is a mixture of mainly alkanes. Alkanes are a group of chemicals which contain
carbon and hydrogen atoms, the smallest of which is methane.
Describe how a mixture of alkanes can be separated using fractional distillation.
[3 marks]
Answer
-Heat or evaporate the crude oil to make it into a vapour [1]
-Cool or condense the hydrocarbons or the fractions [1] or small molecules at top and / or large
molecules at bottom
At different temperatures or boiling points [1] (a) (i) The alkane methane has the following
structural formula.
Draw the structural formula of propane in the box above. [2 marks]
(a) (ii) Alkane are described as consisting of saturated hydrocarbon molecules.
What is the meaning of saturated hydrocarbon molecules? [2 marks]
Answer: Hydrocarbons that contain hydrogen and carbon only. [1] AND no double bonds [1]
between the carbon atoms. [1]
(Total 7 marks)

Burning Hydrocarbons AND Environmental Problems Associated With The Burning Of
Hydrocarbons
4. Some alkanes can be burned and used as fuels. A way to represent the complete combustion of
an alkane fuel is shown by the following word equation.
alkane + oxygen → compound x + water
( a) (i) Name compound x. [1 mark]
Answer: Carbon dioxide [1]
(a) (ii) Hexane is an example of an alkane that can be burned as a fuel. One reaction of hexane
burning in air is shown below.
xC6H14 + yO2 → yCO + xH2O
Balance the equation.[1 mark]
_____________________________________________________________________________
Name the carbon compound produced in this reaction. [1 mark]
Answer: Carbon monoxide [1]
(a) (iii) Suggest a reason for this carbon compound being produced. [1 mark]
Answer: Burned in low oxygen conditions or only partial or incomplete combustion. [1]
(b) The table shows the elements that are present in a sample of crude oil. These elements
can also be present in the fractions produced from this sample crude oil.
Element Carbon Sulphur Nitrogen
% of each element 85 14 0.5 0.5
(b) (i) Name the missing element. [1 mark]
Answer: Hydrogen [1]
(b) (ii) When fractions from crude oil are burned in air, new compounds are made. These
compounds can sometimes cause pollution.
Describe how burning fractions from crude oil can cause pollution. Use the table to help
you. In your answer you should name the compounds produced. [5 marks]

Note: When ANY organic substance is burnt the elements in these substances are converted to
their OXIDES.
ANSWER
Burning Hydrocarbons:
a. Produces carbon dioxide [1] which causes the green house affect or global warming [1]
b. Produces sulfur dioxide [1] which causes acid rain [1]-sulphur dioxide dissolves in
rainwater to form sulphuric acid.
c. Produces nitrogen oxides: nitrogen monoxide AND nitrogen dioxide. NO2 produces acid
rain (nitric acid). [1]
(c) Burning fuels can sometimes cause the release of small solid particles (particulates).
It has been suggested that this can lead to global dimming.
What is global dimming? [1 mark]
Answer: Reduction of light or light being blocked or less light getting to the Earth caused
by particulates in the earth’s atmosphere [1]

What are the causes of Global Dimming?
 Gas Absorption: gases in the atmosphere that absorbs sunlight.
i. Nitrogen Dioxide (NO2)
ii. Methane (CH4)
iii. Carbon Dioxide (CO2) : main absorber of sunlight.
 Water Vapor
 Air pollution(caused by particulate matter in the atmosphere-SO2, ash, soot etc)
(d) State THREE possible environmental effects of global dimming
i. Decrease in sunlight or solar radiation which will negatively impact the process of
photosynthesis in plants.
ii. Global Dimming cause severe weather pattern changes which result in extreme
droughts in various areas.
iii. Global dimming contributes to less solar radiation and results in bouncing back the sun’s
rays and reduce the global temperature.
Cracking Hydrocarbon
Definition cracking: Cracking, as the name suggests, is a process in which large hydrocarbon
molecules are broken down into smaller and more useful ones, for example:

4. Fractional distillation produces different fuels that can be used for heating, transport and
electricity generation. Some of the fractions produced are less useful and so are in less demand.
Thermal decomposition/thermal cracking is used to make the less useful fractions into more
useful ones.
(a) (i) What is thermal cracking ? [2 marks]
Answer: Breakdown of a hydrocarbon [1] by into smaller more useful molecules by means of
heat and high pressure.[1]
(a) (ii) Thermal decomposition is part of the process called cracking.
Explain in detail why cracking of crude oil fractions makes them more useful. [5 marks]
Answer:
 Large molecules made or broken down into smaller molecules [1]
 Smaller molecule more useful [1] as fuels [1]
 Compounds with larger molecules do not flow easily [1]
 Compounds with larger molecules in less demand or compounds with smaller
molecules in more demand.[1]
 To produce alkenes or named alkene, e.g. ethene. [1]
 To make polymers or plastics. [1]
(b) The following equation represents the cracking of decane.
C10H22 → + C2H4
(i) Complete the equation to show the other product of this reaction. [1 mark]
(ii) The product shown is an alkene. It can be tested using bromine water (bromine dissolved in
water). Describe the test that can be used to identify the product as an alkene. [2 marks]
Answer: (Add bromine water), colour change from orange [1] to colourless [1]
Source: my-GCSEscience.com
Ethanol is a flammable liquid that can be used as a fuel for cars. One method for

producing ethanol is by first producing ethene. Ethene comes from the cracking of long
hydrocarbon chains found in crude oil. Ethene is then converted to ethanol.
5 (a) (i) Describe how ethene is converted to ethanol. [2 marks]
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(a) (ii) In this question you will be assessed on using good English, organising information
clearly and using specialist terms where appropriate.
Another method for producing ethanol is from the fermentation of sugar from sugar cane
plants. The method is described below.
• Sugar cane plants are grown as a crop on farmland.
• Sugar cane plants are crushed and soaked in water to produce a sugar solution.
• The sugar solution is separated from the plant material.
• Yeast is added to the sugar solution and fermented.
• The yeast is separated from the solution of water and ethanol.
• Ethanol is separated from water by fractional distillation.
Compare the production of ethanol by fermentation and by using crude oil. In your
answer, include environmental, economic and social factors. [6 marks]
Note: Your response should include a detailed description of the advantages and /or
disadvantages of environmental and economic or social factors. Name of the catalyst not needed.
Manufacture Of Ethanol
Disadvantages of ethanol production using crude oil
Environmental
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Economic / Social:
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Advantages of ethanol production using crude oil
Environmental:
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Economic / Social:
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6. The figure below shows the displayed structures of five organic compounds, A, B, C, D and E.
(a) Choose which organic compound, A, B, C, D or E, matches the descriptions.
You may choose each compound once, more than once or not at all.
Write the letter of the compound that:
(i) is a saturated hydrocarbon. ________ (1)
(ii) comes from a homologous series with the general formula CnH2n ._______ (1)
(iii) has the empirical formula C2H6O. ________ (1)
(iv) has a fruity odour. _________ (1)

(v) reacts with calcium carbonate to produce carbon dioxide. _______ (1)
(vi) reacts with compound D to produce compound C._______ (1).
Write a balanced equation for parts (v) and (vi).
_____________________________________________________________________________
_____________________________________________________________________________
(2)
Total 15 marks
7. Hydrocarbons can be cracked to produce smaller molecules. The following equations
represents the cracking of large hydrocarbons.
(a) Complete the equations to show the other product in EACH reaction.
a. C10H22 → C2H4 +
b. C18H38 → + C4H8 + 2 C3H6 + C2H4
c. C6H14 → C2H4 + + CH4
[3marks]
(b) Compound B (C2H4) and C8H18 are produced by cracking C14H30
C14H30 → 3C2H4 + C8H18
(i) Give two conditions for cracking.
______________________________________________________________________________
______________________________________________________________________________
[2 marks]
(ii) Explain why C8H18 has a lower boiling point than C14H30 .
______________________________________________________________________________
______________________________________________________________________________
___________________________________________________________________ [2 marks]

(c) Compound B is a colourless gas.
Give a chemical test and its result to show that compound B is unsaturated.
Test _______________________________________________________________
___________________________________________________________________
Result _____________________________________________________________
___________________________________________________________________ [2 marks]
(d) Compound B is ethene.
(i) Complete the equation to show the formation of poly(ethene) from ethene.. (2)
(d) (ii) Read the following information.
Landfill,Incineration,Recyclingand Re-use of Poly(ethene)
People couldbe encouragedtore-use theirpoly(ethene)bagsand containers.
Recyclingpoly(ethene) savesraw materialsandenergyneededtomake new plastic.
Whenpolymersare recycledthe plasticsmustbe collected, transported,sortedinto
differenttypesbyhandandwashed.Thisrequires the use of fossil fuelsandisexpensive.
Poly(ethene) canbe burntinan incineratorwithotherhouseholdwaste.The heat
releasedcouldbe usedtomake steamtodrive an electricgenerator. Surplusheatcould
be used to heatgreenhousesusedforgrowing vegetables.Incinerationattoolow a
temperature canproduce harmfulsubstances.The residue (ash) hastogo to landfill.
Landfill isprobablythe easiestwaytodispose of polymersanditischeap. Polymersare
oftenmixedinwithotherhouseholdrubbish.Householdwaste oesnotgetsortedinto
differentmaterialsbecause itisdisposedof inthe same hole inthe ground.Whenthe
hole iseventuallyfull,the waste is coveredbyalayerof soil to stopit smelling.The waste
getscompressed underitsownweight.Mostpolymers,suchaspoly(ethene),are not
biodegradablesowill remaininthe groundforever.

8. You are asked to decide which option for the disposal of poly(ethene) will be put forward in
your area. You decide that recycling is the best option.
Suggest one economic argument and one environmental argument that will be made against
recycling. For each argument made, how will you persuade those making the argument to accept
your option?
(You must use only ONE sentence for each argument made against your decision and only
ONE sentence for your response to it.)
Economic
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Environmental
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[4 marks]
Total 15 marks

(e) Figure 1 shows a short section of the polymer polyvinyl chloride (PVC)..
Figure 1
PVC is produced from a monomer that contains two carbon atoms.
Draw the structure of the monomer. [2 marks]

Grade 11 org. ques, polymerisation

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Grade 11 org. ques, polymerisation