chemistry module c1 answers - wikispacesanswers+c1c2c3.pdfchemistry module c1 answers c1_01 the air...

OCR 21st Century Science C1 Answers

COLLINS NEW GCSE SCIENCE © HarperCollinsPublishers Ltd 2011

Chemistry Module C1 Answers

c1_01 The air around us

Student Book answers

Q1 Nitrogen, oxygen, argon, water vapour, carbon dioxide, other gases.

Q2 Air is a mixture of gases; clouds and dust are not gases.

Q3 The particles get pushed closer together.

Q4 21 m3

Q5 a To enable a better estimate of the true value by calculating the mean of several measurements.

b There is always variation in experimental data because of errors in measurement.

c 20−22 %

d 21%; the mean of the values is the best estimate of the true value.

Practical sheet answers Q1 To make the copper react with the air.

Q2 To push the air to and fro over the hot copper.

Q3 Some of the air/the oxygen has been used up reacting with the copper.

Q5 Errors in measurement cause variation in the results.

Q7 The mean of the results

Q9 The volume increases at first; the air is heated and expanded because the particles are moving faster and

exerting a higher pressure on the syringes.

Q10a Not all the oxygen has been used up; not enough copper used or not heated for long enough.

b The air has not been pushed into one syringe; air is leaking out from the joints in the apparatus. After the air

has been allowed to cool and the volume measured it should be reheated and the measurement repeated until

the final volume remains constant; if there is a leak, the volume will continue to decrease.

c1_02 Changing air


Q1 Water vapour, carbon dioxide

Q2 They assume that the ancient volcanoes gave out the same gases as volcanoes on Earth today.

Q3 Organisms (plants) took in carbon dioxide and gave out oxygen during photosynthesis.

Q4 Living: sea creatures used the carbon dioxide to build shells of calcium carbonate, which form sediment when

they die; or photosynthesising organisms take in carbon dioxide to grow and when they die become fossil fuels.

Non-living: carbon dioxide is dissolved in seawater and combined with calcium to form calcium carbonate that

forms sediment.

Q5 They found evidence in rocks all over the Earth; many scientists interpreted the data in the same way.

Q6 Scientists discovered new evidence in rocks, which showed that earlier ideas were incorrect.

Worksheet answers Activity 3 (High demand)

Q1 Sources of evidence changed from the atmospheres of other planets to volcanoes and rocks on Earth.

Q2 They do not agree that his mixture of gases represents the early atmosphere of the Earth.

Q3 It took years to accumulate evidence that the Earth’s atmosphere was originally largely water vapour and

carbon dioxide.

Q4 Gradually; scientists tend to wait until evidence is overwhelming before they adopt a new theory.



c1_03 Humans and the air


Q1 Road (lorries, buses, cars), train/rail, ships, aircraft

Q2 For example using any electrical appliance, heating, cooking, travelling by car (‘farting’ could be considered

acceptable).

Figure 2: Tractors burn fossil fuels; ploughing can release gases from rotting vegetation

Q3 Carbon monoxide, nitrogen oxide(s), sulfur dioxide, carbon dioxide

Q4 Natural – volcanoes, dust storms, forest fires; human – burning fuels (or any machine that burns fuels)

Q5 In the range 70−75 ppm

Q6 There is a higher number of vehicles in the city/ more industry in the city/ more fossil fuels burned in the city.


Q1 Increasing positive gradient; a curve showing that the rate of increase is increasing.

Q2 Around 450 ppm

Q3 Annual changes; in summer, plants are growing and photosynthesising and taking in CO2 so the concentration

falls; in winter less photosynthesis happens so CO2 concentration rises.

Q4 About 5 ppm

c1_04 Air quality and health


Q1 Sulfur dioxide, carbon monoxide

Q2 More people will suffer asthma attacks and die.

Q3 Greater use of fossil fuels/ more vehicles/ factories burning fossil fuels

Q4 Acid rain; climate change

Q5 The worse the air quality, the more people die from heart/lung diseases.

Q6 Greater in the cities; greater use of polluting vehicles in the cities.

Worksheet answers Activity 1 (Low demand)

Q1 1990s

Q2 Population increased; they burned more fossil fuels.

Q3 1990s

Q4 The increase in deaths followed the worsening air quality.

Activity 2 (Standard demand)

Q1 250−320

Q2 Not good; sulfur dioxide and particulates in the air

Q3 It returned to ‘normal’/similar levels.

Q4 Yes, there is a correlation; the shapes of the graphs are similar; but the air quality does not necessarily cause

deaths.

Activity 3 (High demand)

Q1 300

Q2 5th 100, 6th 300, 7th 600, 8th 610, 9th 500, 10th 250, 11th 240, 12th 190, 13th 200, 14th 170, 15th 150

Q3 2100

Q4 No

Q5 The second figure, ‘up to 12 000’; over 2000 died during the smog itself but the number of deaths continued to

remain high and may well have reached 12 000 over the next few months.

Q6 Yes – there is evidence of a correlation; No – the smog cannot be said to be the cause, but it accelerated

deaths from other causes.



c1_05 Burning fuels


Q1 Carbon dioxide, water/hydrogen oxide

Q2 Hydrogen

Figure 2: flames, smoke rising, ashes being formed; may also see liquid running out of the wood.

Q3 (a) methane + oxygen → carbon dioxide + water; (b) methane reacts/combines with oxygen

Q4 They couldn’t see the oxygen in the air reacting; there wasn’t enough evidence to convince them; they were

unwilling to consider new ideas; they didn’t believe Lavoisier.

Q5 Pure oxygen reacts faster with hydrogen; reaction with pure oxygen gives out more energy per second.

Q6 Pure oxygen is piped to it and the temperature is hot enough for it to keep burning.


Q1 Copper sulfate turns blue/ cobalt chloride paper turns pink.

Q2 It turns cloudy/ milky.

Q3 Fuel; compound; carbon; hydrogen; water; carbon dioxide

Q4 Oxygen


Q1 Priestley (phlogiston) – fuel loses something, air not actively involved; Lavoisier – oxygen in air needed for

combustion, fuel combines with oxygen.

Q2 A mercury + oxygen → mercury oxide (oxidation); B mercury oxide → mercury + oxygen (reduction)

Q3 The metals have combined with oxygen.

Q4 magnesium + oxygen → magnesium oxide; copper + oxygen → copper oxide; iron + oxygen → iron oxide


Q1 The oxygen theory explained the observations better – e.g. increase in mass of oxide, part of air used up.

Q2 Priestley still thought that the phlogiston theory explained the observations; he was old; he may not have liked

Lavoisier.

Q3 Other scientists were able to follow his experiments in his books and copy them.

c1_06 Rearranging atoms


Q1 (a) coal (b) air

Q2 The numbers of each element’s atoms is the same on both sides; C = 1, H = 4 and O = 4.

Q3

Q4 97 g; the zinc and sulfur atoms join together to form zinc sulfide.

Q5 No; variation in measurements means that the true value is not recorded.

Worksheet answers Q1 Carbon dioxide:1C, 2O; water: 2H, 1O; methane: 1C, 4H

Q2 Reactants are hydrogen and oxygen; product is water

a) H is 4, 4; O is 2, 2; b) they are the same; 4; c) the numbers don’t change

Q3 Copper atoms join with oxygen atoms to form copper oxide; oxygen molecules broken into separate atoms.

Practical sheet answers Q1 They have joined up with the oxygen atoms

Q2 Should show an increase

Q3 magnesium + oxygen → magnesium oxide



Q4 They are subject to experimental errors.

Extension

Q5 Theoretical percentage increase is 167%.

Q6 Variation in the results because of different errors.

Q7 You can’t find the true value; but the mean should be close to it.

Q8 The mass of the magnesium oxide formed is equal to the sum of the mass of magnesium and the mass of the

oxygen taken out of the air (or similar).

c1_07 Reactants and products

Student Book answer

Q1 Sulfur – solid, yellow, no smell, insoluble in water.

Sulfur dioxide – gas, colourless, smelly, soluble in water.

Q2 Change of colour, new substance formed, heat/flame produced.

Figure 2: a blue flame; small amount of smoke formed; evidence of melting

Q3 Appropriate differences depending on choice of fuel: coal – black solid; oil/petrol/diesel – coloured liquid;

natural gas – colourless gas. Products: carbon dioxide – colourless gas, turns limewater cloudy; colourless

liquid.

Q4 Less sulfur dioxide is formed when natural gas is burned.

Q5 More fossil fuel was being burned so more sulfur dioxide entered the atmosphere; causing more damage to the

environment.

Q6 Natural gas contains less sulfur than coal so produces less pollutants/sulfur dioxide when it is burned; it is a

cleaner fuel/less environmental damage is caused by burning natural gas.

Practical sheet answers Q1 Glowing/heat given off; colour change.

Q2 Colour – iron sulfide is black, iron is grey, sulfur is yellow.

Magnetism – iron sulfide and iron are magnetic, sulfur is not magnetic.

Water – iron sulfide and iron sink, sulfur floats.

Q3 Iron + sulfur → iron sulfide

Q4 a) Iron sulfide is quite different from iron and sulfur (appearance especially).

b) The mixture shows the properties of both iron and sulfur (e.g. magnet and water separate the iron from the

sulfur) .

This is because in the mixture the iron and sulfur atoms exist separately, but they are joined together in the iron

sulfide.

c1_08 Sources of pollutants


Q1 Carbon dioxide, carbon monoxide, sulfur dioxide, particulates/soot, nitrogen oxides

Q2 Carbon monoxide and particulates

Q3 They have different formulae/ different atom arrangements/ different numbers of oxygen atoms in the molecule.

Q4 Similarity – both have two oxygen atoms; difference – the molecules have different shapes.

Q5 a) Transport; b) industry; c) carbon monoxide

Q6 Nitrogen oxide – air (nitrogen/oxygen mixture) at high temperatures; nitrogen dioxide – nitrogen oxide and

air/oxygen, low/normal temperature


Q1 Bar chart – check scales and values.

Q2 a) Natural gas; b) oil; c) oil; d) coal; e) oil



Q3 For example carbon dioxide is formed when fuels burn in power stations, transport and homes; carbon

monoxide is formed when fuels burn in a poor supply of air, mainly in transport.


Q1 See Student’s Book p.120 Figure 2 for correct molecular shapes.

Q2 Check for suitable axes and accurate plotting; there is a correlation – although not particularly smooth.

Q3 There is not a strong correlation between the amounts of CO and NOx with engine size – the amounts of these

gases are related to engine temperature and efficiency.

Q4 Depends on data chosen but it should match the answers to Q2 and Q3.


Q1 Most of the NO produced in the car engine becomes NO2 on cooling in the atmosphere, so it is fair to give the

total amount of NO and NO2 emitted in the data.

Q2 Depends on vehicles chosen. NB:, the units in the VCA website for particulates are in g/km for particles below

10 µm in size.

c1_09 Removing pollutants


Q1 Wind blows the polluted air away; rain washes a lot of the pollutants out of the air.

Q2 To see the variation in the data.

Q3 It settles on the plants, ground and buildings or is washed out of the atmosphere by rain.

Q4 Mean = 17; range = 15–19

Q5 Wind can carry the pollutants a long way before it falls as rain.

Q6 The variation is large but none of the results are obviously outliers; there is a pattern – a rise and fall.


Q1 There is always variation from the true value because of errors caused by changes in conditions.

Q2 Depends on students’ results; particulate pollution may be higher near a busy road or the flue from an oil or

solid fuel fired boiler.


Q2 The mean should be close to the true value; the range represents the precision or reliability of the results; a

large range suggests a high level of error and an unreliable mean.

Q3 The data vary through the day because of changes to conditions (weather, traffic).


Q1 There may or may not be outliers in students’ results. Outliers should be discarded if they can be shown to be

due to errors in the measurement – e.g. miscounting the number of particles, or someone stuck a grubby finger

on a square of the sticky card.

Q2 There are daily patterns in the variation of air quality data – e.g. for rush hour traffic – but patterns are rarely

smooth because of other variations, some of which may be outliers. Occasional null results from failure of the

equipment can be discounted as outliers.

Q3 Students should identify the damage to trees and freshwater organisms by the low pH value of the water and

leaching of toxic metals into water.

c1_10 Improving power stations


Q1 Turn appliances off when not in use; use low-energy light bulbs; buy new high-efficiency appliances.

Q2 More efficient appliances; new low-energy lighting.

Q3 Coal replaced by other fossil fuels that can have sulfur removed easily.

Q4 Made it more expensive.

Q5 Limestone has to be obtained from quarries, which in turn damage the environment; converting the limestone to

lime uses energy and releases carbon dioxide.



Q6 Scientists have found ways of cleaning up fuels, of removing sulfur dioxide from waste gases and developed

electrostatic filters; they have also developed more efficient appliances and lights.

Practical answers Higher tier only

Q1 The fizzing stopped; the pH indicator turned green.

Q2 The pH indicator turned green or blue.

Q3 Similarities: both remove the sulfur dioxide from the flue; both produce carbon dioxide gas.

Differences: lime/limestone process produces a solid residue that can be sold; limestone has be quarried; no

solids to deal with in the seawater process; seawater process can only be used in coastal power stations.

Which is best is the student’s own opinion but his should be justified. The seawater process is cheaper but

students may consider that it adds to the pollution of the sea by adding sulfate to the seawater. Both processes

add to the amount of carbon dioxide in circulation.

c1_11 Reducing carbon dioxide


Q1 Reduces heat escaping so less fuel is needed to keep the temperature up.

Q2 Fossil fuels are not burned so no pollutants; healthier; less traffic so fewer accidents, etc.

Q3 As the biofuel plants grow they absorb carbon dioxide from the air; when the biofuel is burned this same

amount of carbon dioxide is released.

Q4 Alcohol; hydrogen

Q5 Alcohol, methane from digestion of biomass; a biofuel takes in as much carbon from the air when it is being

cultivated as it gives out when it is burned.

Q6 Scientists have investigated: the cost of obtaining and using fuels; the environmental benefits of using

alternative fuels with fossil fuels; ways of sustainably sourcing alternative fuels, etc.


Q1 Designs should include reduction in fossil fuel use; cleaner air; improved health; saving money; less traffic;

fewer accidents.

Q2 Roof – loft insulation; windows – double/triple glazing; walls – cavity insulation or insulating building materials;

floor – insulation; doors – draughtproofing and/or add a porch.


For – A, B and E; against – C, D and F


Q1 For equal masses, methane contains less carbon.

Q2 Less carbon dioxide produced; gas is easier to transport; burns more cleanly (less SO2, CO, soot formed).

Q3 Natural gas is non-renewable, a limited resource. Methane from biomass is renewable, comes from waste

materials. Natural gas is a short-term, partial solution to the CO2 problem. Future policies will have to move

away from natural gas.

c1_12 Improving transport


Q1 More expensive fuels; road and parking charges; public transport cheaper and more frequent.

Q2 Stops vehicles that exceed the allowed amount of pollution from being used; so keeping emissions below the

accepted level.

Q3 The proportion of useful energy obtained by burning the fuel.

Q4 The % of carbon monoxide produced fell as the number of catalytic converters increased; suggesting the two

factors are correlated.

Q5 No pollutants are emitted; fossil fuel resources not used; can be almost carbon neutral.

Q6 a) Limited range; lack of recharging/refuelling stations



b) Land use poses environmental problems.


Q1 Increases; increases; small; increasing

Q2 a) Sulfur; b) pollutant ; c) public transport/buses


Q1 Small steady decrease; then a large decrease.

Q2 Carbon monoxide emissions decreased after the introduction of catalytic converters.

Q3 Carbon monoxide emissions were falling (slightly) even before catalytic converters became law (despite a rise

in car use).

Q4 Only new cars had to have catalytic converters fitted; not all cars.

Q5 There were still many older cars on the roads that did not have catalytic converters fitted.

Q6 Acts as a catalyst; speeds up the reaction between the pollutants.

Q7 Carbon monoxide gains oxygen; nitrogen oxides lose oxygen.

Q8 Sulfur ‘poisons’ the catalyst stopping it from working.

Q9 It stops cars that exceed the allowed emissions from being used.




c2_01 Using materials


Fig.1 Rubber soles have to be springy/elastic and have good grip.

Q1 It is elastic/springy

Q2 Nylon rope is strong

Fig.2 Plastics can be moulded into intricate shapes but are quite hard and strong.

Q3 a) No; b) B, A, C

Q4 The mean is 140°C; the mean is close to the true value

Fig.3 Fibres are strong and can withstand the force of the wind but are not too heavy.

Q5 Perspex

Q6 Polypropene is stronger/will be able to carry more weight without breaking.

Practical sheet answers Q1 a) The mean of the measurements will be close to the true value.

b) The smaller the range, the less error in the mean and the more likely it is to be close to the true value (or vice

versa).

c) Outliers are considerably different to other measurements in a set.

Q2 Answers depend on the materials chosen – e.g. plastic used for pens; quite hard so wears well, high enough

melting point so remains solid t room temperature, stiff enough so doesn’t bend too easily.

Extension

Q3 The diameter of the threads to calculate the cross-sectional area; the tensile strength depends on the thickness

of the thread.

Q4 a) The size of the error depends on the size of the weights used – e.g. if 1 N weights are used the error in the

measurement is 1 N; procedural errors may arise in the way the threads were fastened to the clamp and the

weight hanger and how the weights were added to the hanger.

b) The error in the balance (at least 0.01 for a balance reading to 2 d.p., more if there is a draught); errors in

reading the measuring cylinder (the error is the smallest division).

Q5 If an error can be identified, the outlier can be discarded.

Q6 Float; density = 18 ÷ 20 = 0.9 g/cm3

c2_02 Choosing materials


Q1 A soft material would wear away more quickly than a hard material.

Q2 Using more material makes the product heavier and more expensive.

Q3 a) HDPE, LDPE, PP – density less than 1 g/cm3; b) LDPE, polystyrene, PMMA, useable temperature is lower

than 100°C; c) HDPE – it is stronger; d) it is hard and strong; e) it softens in hot water; f) it is hard and strong

Q4 It is a strong material.

Q5 PP is quite soft so feels comfortable; in jackets it doesn’t have to be very strong (or similar answers).

Q6 Yes; the data comes from measurements carried out on many times.

Practical sheet answers Standard demand

Q1 All the materials may have shown some elastic behaviour; i.e. shrank after removing the weight.

Q2 Stretching increases the capacity of a bag.

Q3 Strong; expands to carry a large amount of shopping; waterproof; either hardwearing (so can be reused);

recyclable.

Q4 a) They do their job so are probably effective.



b) Probably not durable in that after one use they may become torn (not a bag-for-life).

Q5 We can never be sure of the true value; there is variation in the results (probably); the mean gives the best

estimate of the true value.

High demand

Q2 a) Benefit – would stretch to full capacity and then return to smaller size after use; disadvantage – if handles

stretch with the weight then the bags may rub against the ground when they are carried.

b) Benefit – strong; disadvantage – may not be waterproof, more expensive.

Q3 There was no control of the thickness of the loops (or the length) so the comparison of extensions and breaking

forces are not valid; there must only be one independent variable – the source of the loop.

c2_03 Natural and synthetic materials


Q1 For example: a) jewellery, cars, bicycle, school furniture, cans, cutlery

b) mugs, crockery, bricks, windows, houses

c) clothes, tyres, plastic bottles, rubbers, curtains

Q2 Metals – body, engine

Polymers – seat covers, dashboard, interior, tyres

Ceramics – windows, brake blocks (a bonus point!)

Q3 For example: cotton, paper, flax, hemp

Q4 Polythene is made from small molecules found in crude oil; wool comes from sheep.

Q5 Synthetic materials can be made in larger quantities more cheaply than natural materials and perform better.

Q6 Synthetic materials can be designed to have the properties needed for a particular purpose.

Worksheet answers

Activity 1 (Low demand)

Q1 Metal strong when stretched bridges and machines

Ceramic strong when squashed building materials

Metal conducts electricity wires for carrying electricity

Polymer very large molecules makes rubbers, plastics and fibres

Q2 Elements: copper, aluminium, lead

Mixtures: steel, brass, bronze


Q1 Natural: cotton (plant), paper (plant), leather (animal), wool (animal), silk (animal)

Synthetic: polythene (oil), glass (minerals), nylon (oil) , concrete (minerals)

Q2 Cotton, paper, leather, wool, silk, polythene, nylon


Q1 Wood/Bakelite; rubber/neoprene; silk/nylon; leather/PVC; cotton/polyester

c1_04 Crude oil


Q1 Crude oil is a mixture of hydrocarbons; hydrocarbons are compounds of carbon and hydrogen (only); synthesis

is the manufacture of substances through chemical reactions (that do not occur naturally); a fuel is a substance

that burns and gives out energy.

Q2 The carbon atoms join up with oxygen atoms to make carbon dioxide; the hydrogen atoms join up with oxygen

atoms to make water.

Q3 C 3, H 8, O 10; the same on both sides; atoms are not created or destroyed.

Q4 C4H10 (butane)

Q5 The atoms in the water molecule add to the ethene molecule.

Q6 It is a source of many small molecules that can be used in synthesis reactions to make more complex useful

molecules.




Q1 compounds; hydrocarbons; carbon; fuels; hydrocarbons; oxygen; water

Q2 a) carbon, hydrogen, oxygen; b) C 1, H 4, O 4; c) 9; d) 9; e) they are the same


Q1 octane + oxygen → carbon dioxide + water

Q2 b) Each additional carbon has two extra hydrogens; c) C5H12, C6H14


Q1 a) Bar chart is suitable; b) 90%

c2_05 Separating hydrocarbons


Q1 A mixture of hydrocarbons that have boiling points close together.

Q2 Gases that condense higher up the fractionating tower have lower boiling points than those condensing lower.

Q3 The diesel fraction has a higher boiling point/larger molecules than the naphtha fraction.

Q4 Between 330 and 490°C.

Q5 98°C (accept between 95 and 100°C)

Q6 Yes; in turn, it is the number of carbon atoms the govern the size of the molecule; when all factors are

controlled the graph shows a positive correlation between the number of carbon atoms and the boiling point.


Q1 A – 4; B – 1; C – 2; D − 6; E – 5; F – 3

Q2 a) Smallest at the top. b) Hottest at the bottom. c) Larger; higher

d) Each fraction contains two or more substances.


Q1 b) The fractionating column has a temperature gradient that separates substances with different boiling points.

c) Gases condense.

d) The temperature is increased gradually; different collecting tubes collect different fractions.

e) As the temperature increases, fractions become darker in colour, more viscous, harder to ignite and produce

a yellower, smokier flame (but all these may not be apparent from the fractions obtained from crude oil

substitutes).

f) Refinery process is continuous; all the crude oil is vaporised before entering the pipestill; different fractions

collected simultaneously; scale.

Q2 Molecules in the range: a) CH4 to C4H10; b) C11H24 to C14H30

Q3 Boiling point increases with size of the molecules.

Q4 a) C20–C70; b) C5–C10; c) C15–C20


Q1 As boiling point increases, the energy possessed by the molecules increases.

Q2 They are mainly liquids; forces hold the molecules together.

Q3 Boiling point increases with the length of the molecule.

Practical sheet answers Q2 As temperature increases, fractions become darker in colour, more viscous, harder to ignite and produce a

yellower, smokier flame (but all these may not be apparent using crude oil substitutes).

Q3 Each fraction is a mixture of molecules with similar sizes, the size of the molecules increases with increasing

boiling point/collection temperature.

Q4 Refinery process is continuous; all the crude oil is vaporised before entering the pipestill; different fractions

collected simultaneously; scale.



c2_06 Making polymers


Q1 Made up of lots of similar links – or monomers.

Q2 The process in which many small molecules (monomers) are joined together to form a polymer.

Q3 C2H4 represents the repeated monomer unit; n shows there are a lot of them joined together; it is simpler than

drawing out the whole molecule, which is thousands of carbon atoms long.

Q4 Nylon is made using two different monomers that link together; polyethene is made from one monomer.

Q5

Q6 25 000 cm; 250 metres


Q1 No, it was an accidental discovery.

Q2 Heat, pressure, oxygen

Q3 A white, waxy solid

Q4 They investigated why their experiment had not turned out how they expected.

Q5 Polyethene was used in the Second World War.

Q6 The molecules of hydrocarbon joined together in a long chain to form a polymer.


Q1 a) Styrene/phenylethene. b) Speeds up the reaction. c) Reactants are heated .

d) The polymer is a solid; the monomer is a liquid; the polymer has a higher melting point.

e) The monomer molecules should be joined at the arrows; the hexagonal C6H5 unit needs to alternate from

one side of the chain to the other.

Q2 a) Translucent white skin appears at the interface between the two layers; which is drawn up onto the glass

rod/tongs to become a (wet) white thread.

b) Should show circles in the bottom layer and triangle in the top layer; meeting at the interface and forming a

chain of alternating circles and triangles; which rises out of the mixture.

Q3 Discoverers: Teflon – Roy Plunkett; Nylon – Wallace Carrothers; Kevlar – Stephanie Kwolek


Q1 a) [C3H6]n; polypropene. b) C2H3Cl; polychloroethene. c) [C2H3(C6H5)]n; polystyrene

Q2 15 000 nm = 15 µm = 0.015 mm

c2_07 Better materials

Student Book answer

Q1 Polypropene has lower density/ is lighter; wears better/doesn’t rust; is cheaper.

Q2 Wood is denser than the carbon fibre composite; a wooden racquet the same size as a modern carbon

composite racquet would be heavy to swing.

Q3 PET is stronger than glass; PET has a higher tensile strength than glass.

Q4 Synthetic polymers are usually cheaper, with a lower density, better strength for their weight, can be moulded

into interesting shapes and can be coloured, wear better, waterproof etc.

Q5 Kevlar has a much higher tensile strength than cotton; can take a greater wind force/can be used in higher

winds.

Q6 Nylon has a much lower density than Kevlar or cotton; sails of similar size are lighter to lift if made of nylon.




Q3 Longer lasting; don’t lose pressure so easily; lighter; don’t get heavy when wet; moulded patterns on the

surface make them fly through the air more reliably.

Q4 Lighter (although wood is less dense than polymers, less polymer is needed because it is stronger); easier to

mould into shape.


Q2 a) Polystyrene is harder so doesn’t scratch or wear as easily as polypropene.

b) Polypropene bottles are lighter; not corroded by fluids.

c) Perspex is lighter; doesn’t shatter like glass.

c2_08 Polymer properties


Q1 There is a force between polymer molecules that pulls them together. The closer the molecules are to each

other the stronger the force. Polymers with a larger force between their molecules melt at higher temperatures.

Q2 The branches keep the molecules apart; so the forces between them are weaker; less heat/lower temperature

is needed to pull them apart.

Q3 In LDPE the molecules are further apart; take up more space.

Q4 MDPE has properties midway between LDPE and HDPE; it is softer than HDPE but is stronger and has a

higher melting point than LDPE.

Q5 PET is strong and has a fairly high melting point; has stronger forces and is more crystalline than LDPE.


a) B; b) B; c) A


Q1 The polyethene chains did not have branches.

Q2 Tupperware was used to store food at room temperature and in the fridge.

Q3 It cracked after a short time.

Q4 Longer molecules would have stronger forces between them; melt at higher temperatures; would be stronger.


a) Weaker forces – lower m.p; weaker

b) Greater crystallinity – stronger forces; higher m.p; stronger

c) Stronger forces – higher m.p; stronger

d) Stronger forces – higher m.p; stronger

c2_09 Improving polymers


Q1 The material needs to be tough enough to stand up to wear and tear.

Q2 LDPE has shorter molecules.

Q3 The plasticiser makes the PVC feel soft and squeezable.

Q4 Raising the temperature does not give the molecules enough energy to break the cross-links so the molecules

cannot become free.

Q5 The bonds between atoms in Kevlar molecules are very strong; Kevlar has rigid, flat molecules that can lie

close together so the fibres have a high degree of crystallinity.

Q6 Polystyrene is transparent and hard.




Q1 Short molecules: Polymer softens in hot water; Polymer stretches and tears easily; Polymer feels soft to touch;

Weak forces between polymer molecules.

Long molecules: Polymer is unaffected by boiling water; Polymer is strong; Polymer is hardwearing; Strong

forces between polymer molecules.


Q1 Insulation for electrical components – non-conducting, tough, does not melt; worktops and cooking utensils –

hard, resists high temperatures; car bodies – strong.

Q2

Modification Effect on structure Effect on properties Examples

Increase chain length

Increased force between molecules

Stronger, higher melting point

UHMWPE in hip joints and chopping boards

Add plasticiser Separates molecules, reducing forces between them

Weaker, softer, more flexible PVC – vinyl flooring, fabrics

Cross-linking Bonds between molecules Stronger, stiffer, high melting point

Electrical components, worktops, rubbers


Q1

Make the polymer more crystalline

Molecules closer together, stronger forces

Stronger, stiffer, higher melting point

Kevlar bulletproof vests

Q2 The drawing process lines up the molecules, so that they have a very high degree of crystallinity.

Practical sheet answers

Q1 PVA is a viscous liquid that flows, whereas Slime is ‘solid’ and keeps its shape for while; Slime can be held in

the hands, manipulated, rolled; it snaps when pulled apart; it bounces; it can be stretched.

Q2 a) Cross-links involve small molecules that form bonds between polymer chains.

b) The cross-links hold the polymer chains together so it is stronger and elastic (it also has a higher melting

point and is less soluble in water than PVA).

c2_10 Nanotechnology


Q1 About 10

Q2 Fingernail; human hair; cell; DNA molecule; carbon atom

Q3 0.1 mm

Q4 10 000 × 0.1 = 1000 nm

Q5 1 000 × 10−9

= 1 × 10−6

m (1 µm)

Q6 5 ÷ 0.25 = 20

Worksheet answers


Q1 a) child, pinhead; b) molecule; c) about 16; d) 5


Q1 a) (i) 106 or 1 million atoms; (ii) 20 × 10

12 atoms; b) approx. 25 000


Q1 100

Q2 a) 1 000 000 or 1 × 106 nm

3 = 1 ×10

−1 m

3; b) 1 × 10

9 or 1 billion,; c) 1 × 10

7 or 10 million

d) (i) 4; (ii) nearly 17 million (16 777 216)

Q3 Make sure students show the relationship between the fractions of a metre accurately; and represent

nanotechnology as the manipulation of individual or small groups of atoms.



c2_11 Nanoparticles


Q1 In soot from burning fuels; from sea spray.

Q2 They are extremely small; have a large surface area.

Q3 They are only a few nanometres in diameter.

Q4 They have a very large surface area compared to their mass/volume.

Q5 Gold nanoparticles have a red appearance; large gold pieces are gold/yellow.

Q6 Volume = 1000 nm3 = 1 × 10

−24 m

3; surface area = 600 nm

2 = 6 × 10

−16 m

2


Q1 Nanoparticles are tiny pieces of a material made up of no more than a few thousand atoms. Nanoparticles are

found naturally, such as particles of salt in sea spray and are found in soot formed when fuels are burned.

Scientists are able to make nanoparticles of substances such as gold which have special properties because

of their very small size. Buckyballs are nanoparticles made up of sixty carbon atoms joined together in a ball.

Q2 Students should use the internet to find out about the sources of nanoparticles, but guide them away from

looking at the applications at this point


Q1 Students should research the discovery of C60 by Harry Kroto et al. or the work on nanotubes.

Q2 Gold – red, silver – yellow, buckyballs – violet. Because these properties are different, other properties may

also differ allowing nanoparticles to offer wider applications.


Q1 100 m2

Q2 Students will discover from the internet that a number of heavy metals are used as catalysts and that gold

particles are being investigated as alternatives to platinum group metals in catalytic converters. Their small size

and large surface area makes them more active/faster to react and hence smaller quantities are required. Steer

students away from other applications of nanoparticles.

c2_12 Making use of nanoparticles


Q1 Prevent smells; socks can be worn for longer; they stop feet being infected.

Q2 Kill the microbes that make food go off.

Q3 Doesn’t leave a white film on the skin.

Q4 Made them stronger without making them heavier; can hit the ball harder.

Q5 150 ÷ 1.5 = 100 times stronger.

Q6 Can be made stronger and stiffer without making them heavier; they can stand up to larger forces without

breaking.


Q1 An antibacterial kills bacteria and an antifungal kills fungi.

Silver nanoparticles are highly active because they are very small.

Water jugs have been made from silver because the water stays fresh.

Silver nanoparticles in clothes kill bacteria that cause smells so they do not have to be washed so often.

Q2 Make sure that the function of the nanoparticles is clear.


Q1 a) Silver has been used for a long time to keep water (and food) fresh and clean wounds.

b) They are much smaller; have a large surface area.

c) To kill bacteria/fungi that make food rot.

d) The silver kills bacteria and fungi that feed on sweat and stains and cause smells.



e) Service personnel, explorers, backpackers, people with medical problems that cause body odour, etc.

Q2 a) A material made up of two different substances with different (and complementary) properties.

b) High strength to weight ratio; strong but light.

c) The nanotubes are very strong; so will resist forces on the material.

d) Other racquet sports, pole vaulting, archery, motor racing, cycling, etc.

c2_13 Staying safe with nanoparticles


Q1 Killing bacteria

Q2 Could be washed off antibacterial cloth; carried into the environment.

Q3 May be able to slip through gaps between skin cells and damage internal organs.

Q4 Student’s opinion with valid arguments about hazards/risks.

Q5 There are health issues from burning fossil fuels and from other natural sources of nanoparticles.

Q6 Could demand more tests on the health and environmental hazards; could restrict the use of nanotechnology

until it is proven that the risk is low.


Q1 For: Silver nanoparticles kill the bacteria and moulds that make food rot, and stop wounds from healing.

Silver nanoparticles in cloth stop the clothes from smelling and could prevent diseases from being passed on.

Clothes containing silver nanoparticles need less washing so saving water and energy and using less

detergent.

The amount of silver washed out of clothes is very small.

Against: Silver nanoparticles could kill useful bacteria that break down sewage in sewage works and

decompose waste materials in landfill sites.

When silver nanoparticles kill bacteria they give off a gas which contributes to climate change.

Silver nanoparticles are very active so only a tiny amount needs to escape into the environment to cause a lot

of damage.

Silver is an element so it will never decompose. Once it is in the environment it will always be there.

Q2 Nanoparticles are used as pigments in sunscreens and cosmetics. The same materials have been used for

many years and have been tested to show that they are safe to use on skin. Nanoparticles of the materials are

much smaller than the particles that have been used in the past and have different properties. The

nanoparticles could slip through the skin and enter blood vessels. Some scientists say that the nanoparticles

could then damage internal organs. Consumer groups think that more testing of products with nanoparticles

should be done before they are sold to the public.


Q2 a) They are more active and behave differently because of their small size; may be able to get into organs more

easily than larger pieces of the same material.

b) The size of the risk depends on how severe the hazard is and the chance of someone coming into contact

with it; even if nanoparticles are a hazard it does not mean that the risk to health is high.

c) More testing; control by law of the use of nanoparticles; monitoring of the population.


Q1 Just because we have been exposed to a hazard for a long time does not mean that there is no risk to health

from natural sources of nanoparticles – e.g. allergies, lung problems. New nanoparticles are different

substances from the naturally occurring examples and have different chemical properties.

Q2 Student’s opinion; with more and more applications for nanoparticles being found, some caution is wise; further

testing is necessary and perhaps laws to prevent the use of a nanoparticles prior to testing are needed.




c3_01 Moving continents


Q1 They see changes in rocks caused by tectonic activity today; they see similar evidence in British rocks formed a

long time ago; so they think that these were caused by tectonic activity.

Q2 a) There are different types of rock in Britain formed under different climate conditions. b) Rocks contain fossils

of animals and plants found in tropical climates.

Q3 There are different fossils on either side of the boundary.

Q4 The direction of the magnetism becomes fixed in the rock as it solidifies; as the rock is carried over the Earth its

direction is altered.

Q5 Similar rocks, fossils, magnetic orientation in both locations.


Q2 Statements referring to weathering and erosion go in the second column, all the rest into the first.

Q3 Rocks of different types will have been formed in different places or at different times


Q1 a) Stories based on the sequence of plate movements shown in the maps.

b) Plate boundaries; igneous rocks; faults and re-alignment of rocks caused by earthquakes; metamorphic

rocks formed by heat and pressure; fossils of organisms living in different climates; (magnetic alignment).

Q2 The positions on the timeline should be something like this:

500mya.A..........400mya.............300mya......C......200mya...D.......100mya..E.......B..present


Q1 Magnetism fixed when rocks cool; alignment changed when continents moved; evidence of where and when

rock was formed.

Q2 The rocks formed in different places; moved together or at different times; magnetic North has moved.

c3_02 Useful rocks


Q1 a) Coal, limestone, salt; b) Easy to transport to the factories.

Q2 Sedimentation – limestone and coal; evaporation – salt; mountain building – limestone; dissolving – salt;

erosion – limestone.

Q3 Coal was formed in hot tropical climates; salt was formed when climates turned hot and dry.

Q4 a) Contains small, smooth grains of wind-blown sand.

b) Made up of shells of animals that lived in the sea and contains other fossil sea creatures; there may be

ripples showing that the rock was formed on the bed of rivers or the sea.

Practical sheet answers Method A

Q1 Calcium carbonate. Q2 Build their shells. Q3 Sink into the sediment; form fossils in the rock.

Q4 Deposited at the bottom of the sea. Q5 It is weathered and eroded.

Method B

Q1 a) Salt is dissolving; b) Rainwater trickling through the rocks would dissolve the salts.

Q2 The Sun

Q3 Salt; probably not pure; it contains some tiny particles of sand that were suspended in the water.

Q4 Blown by the wind.




Q1 Coal – burning in steam engines; limestone – building and farming; salt – flavouring and preserving food.


Q1 Rock cycle diagram; coal – sedimentation and compression; limestone – sedimentation, compression, uplift,

weathering, erosion; salt – dissolving, evaporation, compression.

Q2 Moved through different climates; which resulted in different rocks being laid down.


Q1 Contains small, rounded grains.

Q2 Waves when the sediment lay at the bottom of a river or sea.

Q3 The age of the rock; the conditions in which the rock formed; the climate at the time.

c3_03 Salt


Q1 Flavouring; as a preservative.

Q2 By evaporating water from sea water.

Q3 To lower the freezing point of ‘water’ so that ice does not form.

Q4 Mining – rock salt is dug out and carried to the surface; solution mining – water is pumped into the salt deposits

and brine is pumped out.

Q5 To prevent subsidence; the remaining salt holds the roof of the mine up.

Q6 For – salt is needed for many purposes; employment.

Against – loss of habitats/high salt concentration kills wildlife; increased transport; possible contamination of

water supplies.

Practical sheet answers Q1 No; errors in measurements mean that they are seldom the true value.

Q2 Undissolved salt; solution left in filter paper; salt spitting from evaporating dish; salt not completely dry.

Q3 More energy will be needed to evaporate the extra water.


Q1 [1] Sea water is run into artificial ponds. [2] The Sun evaporates some of the water off. [3] The salt water is run

from one pond to another becoming more concentrated. [4] More water evaporates and solid salt begins to form

on the bottom of the pond. [5] The remaining sea water is let out of the pond. [6] The solid salt is shovelled into

heaps to dry out.

Q2 Treating roads in winter.


Q1 Intense sunlight; little rainwater to dissolve the salt or reduce evaporation.

Q2 Fewer impurities; solution piped directly to factory; less labour intensive/automatic.

Q3 Students could access the Lion salt works website; answers could include an account of solution mining and a

description of the evaporation process in open heated pans.


Q1 33%

Q2 Benefits – reduced costs of travel; deaths/injuries prevented.

Problems – costs to councils (unpredictable); environmental effect of mining and transport of salt; effects of salt

on machinery and on wildlife on roadsides.

c3_04 Salty food – benefits and risks


Q1 High – vegetable soup, sausages, baked beans; Low – milk, bread (or any fruit or vegetables).

Q2 To preserve it/keep it fresh.

Q3 62 000 000 ÷ 1000 = 62 000 (actually it is closer to 67 000).



Q4 Although the chance of having a stroke is fairly small (1 : 1000), the outcome is very severe (death); so a high-

salt diet carries a high risk.

Q5 The amount of salt in various foods; symptoms and chances of getting various diseases; suggestions for low-

salt diets.

Q6 For – people will be healthier; lower cost to the health service; Against – civil liberties; difficult to monitor as

some salt is necessary in diets; difficult to set a ‘safe’ limit in specific foods because everyone eats a mixed

diet.

Q7 They like the taste; but do not recognise the risk as being high.

Worksheet answers


Q1 a) (i) 2; (ii) 3 g; (iii) 2 g; (b) the soup; (c) 5 g

d) He will probably exceed the 6 g; reached 5 g with one small meal.


Q1 By 4 g; Q2 25%

Q3 Salt is still a hazard; the risk is reduced.

c3_05 Alkalis


Q1 Ashes of burnt plants; urine.

Q2 The acid is neutralised and a salt is formed.

Q3 Making soap; making glass; treating acid soils; dyeing cloth.

Q4 Was required by soap boilers and glass makers.

Q5 Test with a suitable indicator; add it to an acid and see if the acid is neutralised.

Q6 Test-dye cloth with ammonia alone, alum alone, and both together – see which produces the cloth with the

fastest dye.

Practical sheet answers Testing alkalis

When the alkali is added to the acid, the colour of the litmus should change when approximately equal quantities

have been mixed.

Q1 a) Red; b) blue

Q2 Answers include sodium hydroxide, sodium carbonate, ammonia, limewater (calcium hydroxide).

Q3 The acid is neutralised by the alkali forming a salt and water.

c3_06 Reacting alkalis


Q1 Iron; textiles; glass; pottery.

Q2 The growing industry required more alkali than could be provided from burning plants.

Q3 Alkalis – potassium hydroxide, sodium carbonate.

Salts: –sodium chloride, potassium nitrate, calcium chloride, ammonium sulfate.

Q4 a) Potassium chloride and water.

b) Sodium nitrate, water and carbon dioxide.

Q5 a) calcium hydroxide + sulfuric acid → calcium sulfate + water

b) potassium carbonate + hydrochloric acid → potassium chloride + water + carbon dioxide.

Practical sheet answers

Part A

Q2 a) Depends on indicator used; pH less than 7.

b) Depends on indicator used; pH greater than 7.

c) Should include sodium hydroxide, sodium carbonate, ammonia, calcium hydroxide.



Part B

Q1 When an alkali takes away the acidity of an acid.

Q2 Similarity – hydroxides and carbonates neutralise acids.

Difference – carbonates fizz/give off a gas when they react, hydroxides do not.

Part C

Q1 Sodium chloride

Q2 sodium hydroxide + hydrochloric acid → sodium chloride + water

Part D

Q1 sodium carbonate + hydrochloric acid → sodium chloride + carbon dioxide + water

Q2 hydroxide + acid → salt + water; carbonate + acid → salt + carbon dioxide + water

Q3 a) potassium hydroxide + nitric acid → potassium nitrate + water

b) sodium hydroxide + sulfuric acid → sodium sulfate + water

c) sodium carbonate + sulfuric acid → sodium sulfate + carbon dioxide + water

d) potassium carbonate + nitric acid → potassium nitrate + carbon dioxide + water

e) calcium hydroxide + hydrochloric acid → calcium chloride + water

c3_07 Making alkalis


Q1 Salt was too expensive to use industrially because of the salt tax; an Act ended the tax in 1823.

Q2 Raw materials – salt, coal, limestone; a factory site; workers; buyers.

Q3 Affected by the fumes of hydrogen chloride and hydrogen sulphide generated by the process.

Q4 The alkali manufacturers wouldn’t spend money to clean up their factories if they weren’t forced to.

Q5 Hydrogen and chlorine are gases, colourless and green respectively; chlorine is a bleach; hydrochloric acid is a

solution and is a strong acid.

Q6 Alkali manufacturers were encouraged to collect as much hydrochloric acid as possible to increase their profits;

the factory surroundings were less polluted; people were healthier.


Q1 Chlorine was valuable commodity and there was lots of waste hydrochloric acid from the alkali industry;

chlorine is a green gas and a bleach; hydrochloric acid is a colourless solution and a strong acid.

Q2 Hydrogen in the hydrochloric acid is oxidised by gaining oxygen to form water; chlorine is oxidised by loss of

hydrogen.

Q3 Yes and no; the Gossage method had been available for years and there was demand for chlorine; the alkali

manufacturers needed the spur of the law to improve their works.

c3_08 Chlorine in water – benefits and risks


Q1 Overcrowded living conditions; drinking water contaminated by sewage.

Q2 Chlorine is a disinfectant; it kills microorganisms.

Q3 a) 26–28; b) 10–12 years

Q4 The probability of death fell; from about 26 in 100 000 (about 1 in 4000) to 4 in 100 000 (about 1 in 25 000); a

fall of over 80%.

Q5 0.05 ÷ 0.2 × 100 = 25%

Q6 People are probably more scared of things they do not understand or are unfamiliar with, such as DBPs in

water; so they overestimate the risk compared with risks they are familiar with.

Q7 Chlorine is a corrosive, toxic gas and can cause a great deal of harm; it can react with substances in water to

make harmful compounds; but it is present in such a small concentration in water that it is a very low risk; the

risk from diseases is greater than the risk from DBPs.



Worksheet answers


Q1 Should mention the dangers of untreated water, the correct dose and the hazard of using the disinfectant.

Q2 Should note the reduction cases of waterborne diseases.


Q1 a) 4000; b) 20 000; c) 7–8 per 100 000; d) 14 000–12 500; e) death rate fell by over 70%.

Q2 a) Accurate bar chart; b) 1 in 1250; c) reduced the risk of catching cholera to 1 in 20 000.

d) Chlorine solution is a hazard; particularly if drunk undiluted (it has happened).

Q3 Work of UNICEF, Médecins sans Frontières etc.


Q1 Risk of bladder cancer in USA is 1 in 6000; risk of cholera in Haiti 1 in 170 (and possibly higher); cancers have

other causes; suggests that risk without chlorination is much greater than the risk of cancers with chlorine.

Q2 a) E.g. fear of flying; the MMR vaccine debacle; smokers who do not give up.

b) People tend to over-estimate the risk of unfamiliar things and under-estimate familiar risks.

c) Education; rules on advertising.

c3_09 Electrolysis of brine


Q1 Chlorine – PVC, water treatment; sodium hydroxide – soaps and detergents, papermaking, aluminium

extraction; hydrogen – fuel, margarine.

Q2 36%

Q3 sodium chloride + water (+ energy) → chlorine + hydrogen + sodium hydroxide

Q4 10 ÷100 × 5 million = 500 000 tonnes

Q5 Water

Q6 Pollutants from burning fossil fuels – carbon dioxide, carbon monoxide, particulates, nitrogen oxides, sulfur

dioxide.

Q7 200 g × 6 million = 1200 million g = 1200 tonnes.

Practical sheet answers Q1 a) Chlorine; b) Hydrogen; c) Sodium hydroxide.

Q2 Has been electrolysed; conducted electricity and decomposed.


Hydrogen – fuel; chlorine – water treatment and making PVC; sodium hydroxide – making oven cleaners.


Q1 Salt, water Q2 Electricity/energy

Q3 Anode – chlorine; cathode – hydrogen

Q4 Separates the two halves of the cell keeping the gases apart.

Q5 Can be reused; more salt can be added to it.

Q6 11.3 million tonnes


Q1 The letter should acknowledge the dangers of mercury but state that losses have been reduced and that the

process will be changed to a membrane cell, which uses no mercury. The letter may also point out the

usefulness of the products.

Q2 Students should discover that mercury is concentrated in the food chain, particularly by fish; and mention the

effects it has on the nervous system. They may refer particularly to the Minamata disaster.



c3_10 Industrial chemicals


Q1 The elements are still present/are not destroyed.

Q2 Sodium cyanide; it is more toxic.

Q3 Mercury absorbed by plants → eaten by fish → eaten by larger fish that travelled to Arctic → eaten by Inuit;

small amounts of mercury accumulated up the food chain.

Q4 What hazards lithium presents; how much is needed to be a danger to health; how much is used; the probability

that it will be released from the batteries; what or who might come into contact with it.

Q5 Some may have hazards that have not been suspected; may be using larger quantities; may be used for

different purposes.

Q6 Answers relating to risk assessments of new and old chemicals; people’s perception of risk; familiar/unfamiliar.

Worksheet answers


Q1 a) D (flammable); b) A (corrosive); c) B (toxic); d) C (harmful)

Q2 Label should say what the product is for; what the hazard is; explain the hazard.

Q3 The main point is that the atom is indestructible; it may get eaten by microbes or animals, washed into rivers,

buried underground, but it always survives.


Q1 Plankton → shrimp → fish → eagle

Q2 Answer based on pyramid of mass; the DDT from millions of plankton ends up in the eagle.

Q3 It does not decompose; is washed by wind and rain and ocean currents around the world.

Q4 Advantages: safer for the environment because they are broken down quickly; do not rise up the food chain.

Disadvantages: do not remain to kill pests over a period of time; have to be reapplied so perhaps more is

needed.

Q5 Use of DDT has been allowed in some places for interior use, where it cannot escape into the environment .

Q7 E.g. disinfectant containing chlorine: 0.1% in the air is fatal if breathed for a few deep breaths; a few grams may

be given off if disinfectants are mixed; low chance if instructions followed but a high chance if disinfectants

mixed; make sure chlorine disinfectants are kept separate from other types; there are alternative disinfectants.


Q1 a) Check safety data; if necessary carry out tests.

b) People more likely to perceive high risks in the unfamiliar; evidence that the new chemical is safer than the

traditional substances – good advertising.

Q2 a) There are alternatives to the LD50 test.

b) No; chemicals in the cosmetics may have been tested in other contexts; traditional ingredients may have

hazards that have not been tested (e.g. soap is an irritant).

c) Use of tissue cultures and microbiological tests.

c3_11 PVC


Q1 Plasticised PVC – electrical insulation; any use of sheet PVC; fake leather.

uPVC – construction-related uses: e.g. pipes, gutters, window frames.

Q2 It is soft and flexible.

Q3 If the baby sucks on the toy the plasticiser can be leached/washed out of the material by saliva and swallowed.

Q4 Tests on lab rats and from fish.

Q5 Pollution from the manufacturing process; fumes from fires; leaching of plasticisers.

Q6 PVC has a high risk because of the answers to question 5; plasticised PVC should be banned because of the

risk from plasticisers; alternatively the many uses of PVC make it too valuable a material to be banned.


Q1 a) Strong/ hardwearing/ tough; b) an insulator/ flexible; c) soft/ flexible/ water resistant;

d) tough/ hardwearing/ can be shaped easily.

Q2 a) 3



b) Contains chlorine as well as carbon and hydrogen.

c) (i) Lots of polymer molecules close together; (ii) Polymer molecules spaced out by smaller molecules.


Q1 Look for points for and against the use of PVC cling film, quality of sources, opinions based on evidence.

Q2 Plasticiser washed out clothes etc. when washed; carried to sewage works; then into watercourses and

absorbed by fish.


Q1 Tests to show how much plasticiser is leached from the polymer; tests (on animals) to find the effects of the

plasticiser; epidemiological surveys to find a link between children using the toys and suffering from poor

health.

Q2 Report should provide evidence for both sides and list any sources used; a limited ban may be justified; a more

general ban will await alternatives to PVC that do the jobs more safely.

c3_12 Life Cycle Assessment


Q1 Crude oil/ petroleum (from rocks).

Q2 E.g. drinks bottles/cans, snack/sweet packets, magazines, clothes, pens, containers for shower gel/cosmetics,

etc.

Q3 a) Plants; b) Animals; c) Rocks (crude oil); d) Plants; e) Rocks.

Q4 Heating the polymer to soften it; running the moulding machinery; cooling water to cool the product;

transporting the polymer to the factory and the product away from the factory.

Q5 a) (ii) higher than (i); b) (ii) higher than (i)

Q6 a) Mining aluminium ore and drilling for oil have similar environmental impacts; more energy required for

aluminium so more pollution from burning fossil fuels.

b) More energy needed to transport glass bottles; more pollution from burning fossil fuels.


Q1 Cork

Q2 PVC

Q3 Cork; it can be burned and is biodegradable.

Q4 PVC lasts longer than untreated cork; it is hardwearing and does not decay.

Q5 PVC advantages – resources available from many places; hardwearing.

Disadvantages – toxic substances produced in manufacture and disposal; non-renewable resource.

Cork advantages – renewable resource; low environmental impact.

Disadvantages – relatively short life if not treated; restricted production.


Students may produce a summary LCA as a diagram or table. Benefits see question 5 above. Overall

environmental impact – PVC is the worst. Final decision depends on student’s arguments – PVC has the longer life

and is more widely available, so despite its environmental impact it may prove to be the best.

Higher-tier students could be encouraged to give scores (1 to 5) to each material for each section of the LCA.


Alternatives – linoleum, carpet (hemp, wool, polypropene), wood; students may provide an LCA for one or more of

these and make a decision on their favoured material; wood or linoleum may be the best.

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