Q1. 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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Q2. In 1939 a scientist opened the valve on a new cylinder of tetrafluoroethene gas. No gas came out.

He cut the cylinder open and found that the gas had changed into a white solid. This solid was an addition polymer.

(a) Give the name of the addition polymer that formed inside the cylinder.

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(b) The structure of this polymer can be represented by the diagram below.

Draw the structure of the monomer, tetrafluoroethene, from which it is formed.(2)

(c) Describe how this addition polymer forms from monomers.

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(Total 6 marks)

Q3. (a) PEX is a material that is used as an alternative to copper for hot water pipes.PEX is made from poly(ethene).

(i) Describe how ethene forms poly(ethene).

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(ii) PEX is a shape memory polymer. What property does a shape memory polymer have?

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(iii) The simplified structures of poly(ethene) and PEX are shown.

Poly(ethene) PEX

Poly(ethene) is a thermoplastic that softens easily when heated.

Suggest and explain how the structure of PEX changes this property.

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(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 distillation2 Cracking3 Polymerisation4 Conversion of poly(ethene) into PEX

Suggest the possible environmental advantages of using PEX instead of copper for hot water pipes.

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(Total 10 marks)

M1. Marks awarded for this answer will be determined by the Qualityof Written Communication (QWC) as well as the standard of thescientific response.

No relevant content.0 marks

There is a brief description of a positive and a negative environmentalimpact involved with one or more methods used to reduce theamount of plastic bags sent to landfill.

Level 1 (1–2 marks)

There is some description of both positive and negativeenvironmental impacts involved with at least 2 methods usedto reduce the amount of plastic bags sent to landfill.

Level 2 (3–4 marks)

There is a clear, balanced and detailed description of both apositive and a negative environmental impact of using each

of the 3 methods used to reduce the amount of plastic bagssent 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

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]

M2. (a) polytetrafluoroethene1

(b)

4 single bonds C-F1

1 double bond C=C1

(c) many tetrafluoroethene monomers / molecules1

join / bond together

accept higher level answer relating to ‘double bond opening’1

to form a very large molecule / chain1

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M3. (a) (i) many ethene / molecules / monomers

accept double bonds open / break1

join to form a long hydrocarbon / chain / large molecule

accept addition polymerisation

ignore references to ethane

correct equation gains 2 marks1

(ii) (can be deformed but) return to their original shape (whenheated or cooled)

ignore ‘it remembers its shape’1

(iii) cross links / extra bonds in PEX

accept inter-molecular bondsignore inter-molecular forces

1

molecules / chains in PEX are held in position

accept rigid structure1

molecules / chains in PEX unable to slide past each other / move

it = PEX throughout1

(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-renewable4

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