Q1. (a) The hydrocarbon C 16 H 34 was heated strongly in the absence of air. This is one of the reactions which took place: C 16 H 34 C 6 H 14 + C 6 H 12 + 2C 2 H 4 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 ................................................................................................................................. .................................................................................................................................... 2 ................................................................................................................................. .................................................................................................................................... (2) (b) A molecule of the compound methane, CH 4 , can be shown like this: Draw a molecule of the compound ethene, C 2 H 4 . (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 1 of 68
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Q1. (a) The hydrocarbon C16
H34 was heated strongly in the absence of air.
This is one of the reactions which took place:
C16H
34 C
6H
14 + C
6H
12 + 2C
2H
4
This type of reaction is carried out because there is a greater demand for the products than for the original hydrocarbon.
Q4. The table shows some of the products which are obtained from the fractional distillation of crude oil.
Fraction Nature of products
A a mixture of gases
B a mixture of low boiling point liquids
C a mixture of high boiling point, yellow liquids
(a) For each of the fractions A–C give the name of an organic substance which could be part of the fraction and state a use for it.
A .....................................................................
Use .............................................................................................................................. (2)
B .....................................................................
Use .............................................................................................................................. (2)
C .....................................................................
Use .............................................................................................................................. (2)
(b) When burned in excess air, all the substances in fractions A–C form the same two compounds.
Give the formulae of these two compounds.
........................................................... and ................................................................. (1)
(Total 7 marks)
Page 3 of 68
Q5. Crude oil is a mixture of long-chain hydrocarbons. It is cracked to produce a mixture of smaller alkanes and alkenes. Among the gases formed are ethane and ethene.
(a) Write the structural formula for:
(i) ethane
(1)
(ii) ethene
(1)
(iii) Give an example of one chemical reaction which both ethane and ethene undergo.
(iv) Describe how to distinguish between ethane and ethene. Include a description of the practical method you would use and what you would expect to observe.
Q8. The diagrams show the percentages of the four main fractions produced from two samples of crude oil, A and B.
Page 6 of 68
(a) The light fraction contains hydrocarbons used for the manufacture of useful chemicals such as polymers. Which one of the samples, A or B, would be more useful for the manufacture of polymers? Explain your answer.
(e) The cracking of large molecules obtained from crude oil is one of the important processes in an oil refinery. Cracking involves the thermal decomposition of large molecules. The diagram below shows an apparatus that can be used to demonstrate cracking in the laboratory. The porous pot acts as a catalyst in the reaction.
Q21. 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).
Complete the balanced symbol equation by writing in the formulae of the two products.
C2H
5OH + 3O
2 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?
(ii) Use the correct word from the box to complete the sentence about ethene.
Ethene is made by breaking down large hydrocarbon molecules into smaller
hydrocarbon molecules by a process called ..................................................... (1)
condensing corroding cracking
(iii) The hydrocarbon ethene has the formula C2H
4
Complete the sentence about ethene.
Ethene is a hydrocarbon made up of carbon and .......................................... atoms. (1)
(b) The hydrocarbons used to make ethene come from crude oil. The properties of hydrocarbons are linked to the number of carbon atoms in their molecules.
Number of carbon atoms 5 6 7 8 9
Boiling point in °C 36 69 99 125 151
Page 25 of 68
(i) Use the data in the table to complete the bar chart.
(2)
(ii) What happens to the boiling point of a hydrocarbon as the number of carbon atoms increases?
Average surface temperature –23 °C Average surface temperature 15 °C
Page 27 of 68
(b) Titan is the largest moon of the planet Saturn. It has an atmosphere that, like the Earth’s, contains mainly nitrogen. Methane is the other main gas.
When it rains on Titan, it rains methane! Explain why.
(c) Ethene is used as the starting material for many polymers. The most common polymer is poly(ethene). One hydrocarbon molecule in poly(ethene) will contain thousands of carbon atoms.
Complete the diagram to show the bonds in ethene.
H H
C C
H H (1)
Page 31 of 68
(d) Read the following information.
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.
Landfill, Incineration, Recycling and Re-use of Poly(ethene)
People could be encouraged to re-use their poly(ethene) bags and containers.
Recycling poly(ethene) saves raw materials and energy needed to make new plastic. When polymers are recycled the plastics must be collected, transported, sorted into different types by hand and washed. This requires the use of fossil fuels and is expensive.
Poly(ethene) can be burnt in an incinerator with other household waste. The heat released could be used to make steam to drive an electric generator. Surplus heat could be used to heat greenhouses used for growing vegetables. Incineration at too low a temperature can produce harmful substances. The residue (ash) has to go to landfill.
Landfill is probably the easiest way to dispose of polymers and it is cheap. Polymers are often mixed in with other household rubbish. Household waste does not get sorted into different materials because it is disposed of in the same hole in the ground. When the hole is eventually full, the waste is covered by a layer of soil to stop it smelling. The waste gets compressed under its own weight. Most polymers, such as poly(ethene), are not biodegradable so will remain in the ground forever.
Page 32 of 68
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.)
Q26. Plastics are used to make many everyday items, such as the body of the kettle.
(a) Complete the sentences by drawing a ring around the correct words.
(1)
(i) The plastic is made from many small molecules called
catalysts
monomers
polymers
(ii) Propene is produced by cracking some of the fractions that are
(1)
separated from
crude oil
limestone
metal ores
Page 33 of 68
(b) After a few years the kettle no longer worked.
• Some parts of the kettle are made of plastic. • Some parts of the kettle are made of stainless steel. • The owner of the kettle disposed of it in a landfill site.
Consider these statements.
Suggest three reasons why the kettle should not be disposed of in a landfill site.
(b) Copper was considered to be the most suitable material to use for hot water pipes. PEX is now used as an alternative material for hot water pipes.
Copper is extracted from its ore by a series of processes. 1 The low-grade ore is powdered and concentrated. 2 Smelting is carried out in an oxygen flash furnace. This furnace is heated to 1100 °C
using a hydrocarbon fuel. The copper ore is blown into the furnace with air, producing impure, molten copper.
3 Oxygen is blown into the impure, molten copper to remove any sulfur. The copper is cast into rectangular slabs.
4 The final purification of copper is done by electrolysis.
PEX is made from crude oil by a series of processes. 1 Fractional distillation 2 Cracking 3 Polymerisation 4 Conversion of poly(ethene) into PEX
Suggest the possible environmental advantages of using PEX instead of copper for hot water pipes.
(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.
(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.
M1. (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
(ii) poly(propene) (N.B. brackets not required; allow “polypropylene”)
for 1 mark 1
[6]
##
(a) Compound A has fewer C atoms or Compound B has fewer H atoms
Compound A has C = C/double bond or Compound A is unsaturated
each for 1 mark (accept converse i.e compound B has not ...)
2
Page 41 of 68
(b) Compound A is reactive or can be used to make many substances or can be used in polymerisation/making plastics/named plastic or can be used as a fuel
any one for 1 mark 1
[3]
M3. (a) C=C
do not accept C2H
4
1
four Hs only, two attached to each carbon credit CH
2CH
2 for two marks
1
(b) C3H
8 + 5O
2 → 3CO
2 + 4H
2O
two correct formulae LHS 1
can be in either order two correct formulae RHS
1
can be in either order correctly balanced, consequential marking allowed for 10 O
1 [5]
M4. (a) Substance Use
A any pair from
award one mark for a correct use for an incorrect fuel
methane or fuel
natural gas or refinery gas
ethane fuel or making ethene for polymerisation
propane bottled or camping gas or fuel
accept relevant trade names e.g. Calor Gas 2
Page 42 of 68
butane bottled or camping gas or fuel or lighter fuel
B any pair from
petrol or gasoline fuel for cars
accept car engines do not credit just cars
naptha petrol or chemicals or feedstock or solvent
paraffin or kerosene heating fuel or aviation fuel
accept jet or aircraft fuel 2
C any pair from
naptha petrol or chemicals or feedstock or solvent
paraffin or kerosene heating fuel or aviation fuel
diesel or diesel oil or (light) gas oil vehicle fuel or heating fuel
(lubricating) oil
lubricating or oiling qualified, eg. oiling a gate
fuel oil
industrial or heating fuel
heavy gas oil
fuel for stationary or slow speed diesel engines
2
(b) CO2 and H
2O
both required 1
[7]
Page 43 of 68
M5. (a) (i)
do not credit CH
3CH
3
1
(ii)
do not credit C
2H
4
1
(iii) burn or react with oxygen or combustion or oxidation
accept react with chlorine 1
(iv) bubble each gas through (test tube containing) bromine water accept add bromine (water to gas collected) or burn
1
ethene decolourises it or turns the brown colourless
accept ethene burns with smoky flame do not accept makes it go clear
1
ethane does not affect it or leaves it brown
accept ethane burns with clear flame note carefully the spelling of ethene and ethane
1
(b) both the correct name and use are required for the mark
poly (ethene) or polythene; any soft or pliable plastic article or any suitable harder plastic item
accept polyethene or polyethylene 1
[7]
M6. (a) hydrocarbon 1
(b) thermal decomposition / cracking 1
Page 44 of 68
(c) (i) making polymers / poly(e)thene accept plastic (bags)
1
(ii) fuel 1
[4]
M7. (a) (i) X and Y
both needed 1
(ii) Z 1
(iii) X 1
(b) unsaturated / alkenes / those with double (C = C) bonds 1
[4]
M8. (a) B because it contains more of the light fraction) 1
Quantitative answer e.g. B has 30%, A has 20% / 10% more / 1.5 times more
1
(b) (i)
1
(ii) heat 1
catalyst if neither mark gained allow cracking for 1 mark
1 [5]
Page 45 of 68
M9. (a) any three from
carbon (atom) spine / chain accept idea of ‘backbone’ of carbon (atoms)
surrounded by hydrogen (atoms) accept idea of only bonded to hydrogen (atoms)
3
single (covalent) bonds between carbon atoms accept no double bonds
saturated (hydrocarbons)
(general formula) CnH
2n+2
(b) many small molecules/ monomers accept many unsaturated molecules or alkenes
1
join together to form a large / long molecule / polymer 1
(ii) saturated since it has single bonds / no double bonds / no multiple bonds / maximum number of atoms attached
for one mark 1
(iii) sensible answer (e.g. it is harmful) or better solvent could be used on expanded polystyrene or foam
for one mark 1
(b) (i) simply writing monomers form / react to form polymers gains no mark monomers join / bond / combine / link to form polymers = 1 mark the mark is for the idea of joining to gain the second mark the idea of the relative size of monomer and polymer is required small molecules join to form a polymer (2 marks) many monomers join to form a polymer (2 marks) monomers join to form a large molecule / long chain (2 marks) many molecules join together (2 marks)
for 1 mark each 2
Page 46 of 68
(ii) polyethene / poly(ethene) / polythene
don’t worry too much about the exact positioning of the C6H5 at the end of the bond
placement of linking bonds inside / outside brackets is not important must have n
for 1 mark each [8]
M11. (a) (fractional) distillation/fractionation
for 1 mark 1
(b) (i) cracking/decomposition for 1 mark
1
(ii) polymerisation/addition reaction for 1 mark
1
(c)
(Must have H atoms) for 1 mark
1
(d) contains only/all single bonds no double bonds contains maximum number of H atoms carbon atoms bonded to 4 other atoms (not 4 H atoms) will not undergo addition reactions
any 1 for 1 mark 1
Page 47 of 68
(e)
(n must be on (right)) = 2 marks
(n on left = 1 mark) = 2 marks
= 1 mark
= 1 mark
(Double bond loses both marks) = 0 marks
OR
= 2 marks
(for both a minimum of 4 carbon atoms) = 1 mark
= 2 marks
Page 48 of 68
= 1 mark
= 1 mark
2 [7]
M12. (a) C2H
4
1
H H H H C C C H H H H
Accept even if in wrong columns 1
(c) (i) polythene or poly(ethene) 1
(ii) addition 1
[4]
M13. (a) A compound made from carbon and hydrogen (not mixture etc.) 1
(b) C5H
12
1
(e) (i) Break down
by heat
(ii) Speeds up reaction
(iii) C8H
16
each for 1 mark 4
[6]
Page 49 of 68
M14. (a) (i) heat
accept increase temperature ignore pressure 1
with a catalyst 1
(ii) 1
accept displayed formulae only
1
(iii) O2
1
CO2 + H
2O
ignore state symbols 1
correct balancing 2 + 7 → 4 + 6
accept 1 + 3 → 2 + 3 only if reactants and products correct 1
Page 50 of 68
(b) double bond breaks 1
many (ethene) molecules
accept many monomers 1
bond together accept join or combine for bond accept
for first 2 marks ignore unsaturated becomes saturated 1
[10]
M15. (a) catalyst 1
(b) (i) made up of only carbon and hydrogen 1
(ii) C8H
18
1
(c) (i) ethene 1
(ii) polymerisation 1
[5]
M16. (a) (i) C4H
10 + Cl
2 → C
4H
9Cl + HCl
reactants 1
products ignore incorrect balancing no state symbols required
1
(ii) substitution / chlorination 1
Page 51 of 68
(b)
H atoms not necessary 1
(c)
2 [6]
M17. (a) (i) by heating
pressure is neutral
using a catalyst/pot/ceramic/porcelain/aluminium oxide 1
(ii) use bromine water/(alkaline) permanganate accept bromine
1
alkene makes bromine go colourless or lose its colour accept alkane does not change the red/orange colour of bromine not change colour/goes clear
1
(b) (i) either of these must show bonds at end
1
or
not H on ends allow 3 instead of n not any other number
Page 52 of 68
(ii) poly(ethene) – brackets not essential accept polythene
1
(iii) large amount of waste polymer/poly(ethene)/polythene/litter
accept large amount of crude oil or finite resource used 1
it is not biodegradable accept it does not decompose/decay/break down it causes pollution/it creates toxic fumes when burnt are neutral not it is not recyclable
2 [8]
M18. (a) poly(tetrafluoroethene) or polytetrafluoroethene
accept PTFE or Teflon 1
(b) double bond
1
all other atoms and bonds correct including F for fluorine
ignore n in front
or = 1 mark
= 1 mark
CF
2 = CF
2 = 1 mark
do not accept structures with more than 2 C atoms 1
Page 53 of 68
(c) any three from:
• many monomers / (small) molecules / tetrafluoroethene molecules allow many tetrafluoroethenes many particles alone is insufficient do not accept many polymers
• (monomers, molecules etc.) join / bond / link / combine / attach allow many particles join allow many atoms join do not accept collide / add ignore polymerise do not accept many polymers join
• to form one molecule or to form a long-chain or to form a large molecule
• no other substances are produced / one substance formed (definition of addition)
• idea of double bond breaking / opening / opens / bond being used to join to another molecule or the double bond becomes a single bond
3 [6]
M19. (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) C8H
18
allow H18C
8
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 54 of 68
(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]
M20. (a) not broken down by microorganisms or not bio-degradable
accept alternative answers such as: do not rot / corrode / fade / react with atmosphere etc any answers which imply the inertness or non-biodegradability of this plastic accept they don’t react, they are ‘inert’ ignore rusting do not accept weathering
1
(b) (i) (have a) double bond or do not have maximum number of (hydrogen) atoms attached
accept can add / react with hydrogen accept can take part addition reactions do not accept it is a double bond do not accept additional reactions do not accept has ‘spare’ / ‘free’ bond do not accept alkene alone
1
Page 55 of 68
(ii) single bond between carbon atoms 1
all atoms correct + 2 ‘linking’ bonds (linking bonds need not go through bracket)
1
n moved to bottom right of bracket i.e. is below way on the right first 2 marks are possible for chain structures accept [– CHCl–CH
2–]
n
1
(iii) many molecules or many monomers 1
joined / bonded / linked or form long chain molecules / large molecules or to form a long chain polymer
accept many alkenes or many (ethene) molecules do not accept many ethene alone etc.
to form a long polymer is not enough for 2nd mark
1
(iv) no other substances formed (A + B → C)
allow because double bond breaks so other atoms can add allow one product only do not accept saturation occurs
1 [8]
Page 56 of 68
M21. (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
(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]
M22. (a) (i) poly(ethene)
accept polythene 1
(ii) cracking 1
(iii) hydrogen 1
Page 58 of 68
(b) (i) bar labelled 9 1
bar drawn to correct height 1
(ii) (boiling point) increases 1
(iii) heat / evaporate (the crude oil) accept separate by boiling point
1
cool / condense (hydrocarbons at different temperatures) accept smaller molecules go to top / larger molecules stay at bottom accept fractional distillation for two marks or distillation / fractionation for one mark
1
(c) yes
any two from:
• because plastic does not biodegrade or running out of space for landfills or land cannot be used for a long time
• it provides heat energy
• which can be used to generate electricity / heat homes or greenhouses
• any other advantage of burning
• any other disadvantage of landfill
or
no
• burning plastic produces carbon dioxide / carbon emissions / toxic gases accept landfill does not produce carbon dioxide / carbon emissions
• causes global warming / climate change / increase greenhouse effect / global dimming / acid rain
• any other disadvantage of burning
• any other advantage of landfill 2
[10]
Page 59 of 68
M23. (a) any two from:
asks for cause therefore no marks for just describing the change must link reason to a correct change in a gas
carbon dioxide has decreased due to: accept idea of ‘used’ to indicate a decrease
nitrogen increased due to: accept idea of ‘given out / produced’
• ammonia reacted with oxygen
• bacteria / micro organisms ignore (increase in) use of fossil fuels / deforestation
2
(b) (because methane’s) boiling point is greater than the average / surface temperature or Titan’s (average / surface) temperature is below methane’s boiling point
ignore references to nitrogen or water 1
any methane that evaporates will condense accept boils for evaporates accept cooling and produce rain for condensing
1
(c) (i)
bonds must be displayed correctly ignore bond angles
1
Page 60 of 68
(ii) poly(propene) / polypropene / polypropylene do not allow polypropane
• form chains / long molecules(*) (*)correct chemical equation gains 2 marks ignore large using monomer incorrectly max 2 marks
2 [8]
M24. (a) (i) hydrogen
must be name 1
(ii) a line of four or more ethene molecules joined to the original two with single bonds
at least two other ethene molecules joined to the original two in a chain gains 1 mark
2
(b) (i) any two from:
• non-biodegradable accept remains a long time
• landfill sites are filling up / limited accept land / space used up
• waste of a resource / could be recycled / reused ignore references to tablets / animals
2
(ii) any one from:
• (two) different polymers / plastics / materials
• need to be separated
• limited collection points / many need to be collected
• tablets may still be present 1
[6]
Page 61 of 68
M25. (a) any two from:
• naphtha has a different / low(er) boiling point accept different volatility
• condenses at a different temperature / height / place in the column / when it reaches it’s boiling point
• different size of molecules 2
(b) (i) C10
H22 → C
6H
14 + 2C
2H
4
allow multiples 1
(ii) (hydrocarbon) heated / vapours 1
(passed over a) catalyst / alumina / porous pot ignore other catalysts
1
(iii) it / ethene is unsaturated or decane and hexane / they are saturated
accept decane and hexane are alkanes / CnH
2n+2
or ethene is an alkene / CnH
2n
or different homologous series / general formula 1
ethene has a double (carbon carbon) bond or decane and hexane have only single (carbon carbon) bonds
accept ethene has a reactive double (carbon carbon) bond for 2 marks
1
(c) all bonds drawn correctly
1
(d) economic argument against recycling
any one from:
• poly(ethene) / plastic must be collected / transported / sorted / washed
• this uses (fossil) fuels which are expensive 1
Page 62 of 68
environmental argument against recycling
any one from:
• uses (fossil) fuels that are non-renewable / form CO
2 / CO / SO
2 / NO
x / particulates
ignore pollution / harmful gases / etc
• washing uses / pollutes water 1
counter arguments
any two from:
• collect / transport alongside other waste
• use biofuels (instead of fossil)
• landfill is running out
• landfill destroys habitats
• incinerators are expensive to build
• saves raw materials / crude oil
• saves energy needed to make new plastic
• incinerators may produce harmful substances
• incinerator ash goes to landfill
• poly(ethene) is non-biodegradable
• poly(ethene) can be made into other useful items
• more jobs / employment for people 2
[12]
M26. (a) (i) monomers 1
(ii) crude oil 1
Page 63 of 68
(b) any three from:
• metal may not corrode away / remains
• plastic remains / does not break down (decay) / not affected by microorganisms accept non-biodegradable
• should recycle / conserve resources / mend the kettle / burn (plastic) as a fuel accept it is a waste of materials / resources
• landfill sites are limited / filling up
• water pollution ignore harms wildlife / habitats or problems caused by burning the kettle
3 [5]
M27. (a) (i) many ethene / molecules / monomers
accept double bonds open / break 1
join to form a long hydrocarbon / chain / large molecule accept addition polymerisation ignore references to ethane correct equation gains 2 marks
1
(ii) (can be deformed but) return to their original shape (when heated or cooled)
ignore ‘it remembers its shape’ 1
(iii) cross links / extra bonds in PEX accept inter-molecular bonds ignore inter-molecular forces
1
molecules / chains in PEX are held in position accept rigid structure
1
molecules / chains in PEX unable to slide past each other / move it = PEX throughout
1
Page 64 of 68
(b) any four from:
• less (hydrocarbon) fuels used allow less energy
• less / no electrical energy used allow no electrolysis
• reduce carbon / carbon dioxide emissions allow less global warming
• reduce / no pollution by sulfur dioxide / acid rain
• continuous process allow less / no transportation
• conserve copper which is running out or only low-grade ores available
• reduce the amount of solid waste rock that needs to be disposed allow less waste
• reduce the need to dig large holes (to extract copper ores) allow less mining ignore costs / sustainability / non-renewable
4 [10]
M28. (a) (i) C2H
4
1
(ii) poly(ethene) 1
(b) (i) is not biodegradable 1
(ii) not enough landfill sites / space accept landfill sites are filling up or plastics remain for years or plastics not broken down ignore cost / waste of resources / not biodegradable / wildlife
1
(iii) less (crude) oil / fuels / energy used accept (crude) oil is a non-renewable resource
1 [5]
Page 65 of 68
M29. (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
(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