1 Using Earth's resources, pot. water 2 2 9 8 75 9 Haber ......accept any in range 55 − 64 • (graph 2 shows) the fluoride ions reduce percentage with decayed teeth • (graph 2

1 Using Earth's resources, pot. water 2

2 9

3 Life cycle assessment + recycling 21

4 30

5 44

6 Using materials 52

7 64

8 75

9 Haber process + use of NPK fertilizers 81

10 90

11 101

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Page 1

Using Earth’s resources; pot. water

Mark Scheme

Level GCSE (9-1)

Subject Chemistry

Exam Board AQA

Topic 4.10 Using resources

Sub Topic Using Earth’s resources; pot. water

Difficulty level Bronze Level

Booklet Mark Scheme

Time Allowed: 28 minutes

Score: /28

Percentage: /100

Grade Boundaries:

A* A B C D E U

>85% 777.5% 70% 62.5% 57.5% 45% <45%

http://www.savemyexams.co.uk/?utm_source=PDF&utm_medium=PDF


Page 2

M1.(a) (i) Filtration 1

(ii) Chlorine 1

(b) (i) nanoparticles are small / smaller / much smaller / tiny

allow any in range 1−100 nm or 1 × 10-9 m − 1 × 10-7 m or a few hundred atoms in size

ignore numbers if stated smaller 1

(ii) they have a high surface area to volume ratio

reference to surface area without volume ratio is insufficient

allow nanoparticles are very reactive or nanoparticles are more reactive than normal particles.

1

(c) (sodium hydroxide) produces a white precipitate

accept solid / suspension or ppt or ppte for precipitate.

ignore cloudy / milky 1

which (then) dissolves / disappears (in excess sodium hydroxide)

M2 cannot be awarded unless a solid of some sort has been made

ignore names or formulae of compounds 1

[6]



Page 3

M2.(a) (i) Solids 1

(ii) Chlorine 1

(iii) kill microbes / bacteria

allow to make the water safe to drink

ignore disinfect

ignore remove / get rid of microbes 1

(b) energy

allow heat 1

(c) improve dental health

allow reduce tooth decay

allow (local) government requirement

allow help teeth 1

[5]



Page 4

M3.(a) (i) Solids 1

(ii) Chlorine 1

(iii) improves dental health or reduces tooth decay 1

(b) put a sample of the filtered water in an evaporating basin or leave to evaporate

accept any description of evaporation (using a Bunsen or leaving on the windowsill)

1

there will be crystals of salt left 1

(c) sodium and / or chloride ions are bigger than water (molecules) or ions are charged or molecules are not charged

do not accept sodium chloride molecules as ions is given in the question

1

[6]



Page 5

M4.(a) (i) economical 1

(ii) phytomining 1

(iii) carbon dioxide 1

(b) (i) copper / Cu 1

iron sulfate / FeSO4

1

(ii) copper / ions have a positive charge

it = copper ions

allow copper ions have a different charge

accept copper / ions are free to move

accept to gain electrons

accept copper / ions are attracted to the negative electrode or opposite charges attract

1



Page 6

(c) any two from:

ignore not biodegradable or does not decay

• copper ores are limited / running out

allow copper is running out • copper can be recycled • copper can be reused • copper is expensive • landfill sites are filling up • copper compounds are toxic

allow copper is toxic 2

[8]



Page 7

M5. (a) contains (large amounts of) dissolved solids / difficult to remove dissolved solids

allow salty / too much salt

allow sea water makes you thirsty / vomit

allow polluted / untreated / contaminated 1

(b) filtered: removes solids / removes insoluble material / dirt

ignore large objects 1

chlorine: kills/destroy bacteria/microbes/ germs etc

allow disinfect / sterilise or gets rid of bacteria

ignore purify / clean 1

[3]



Page 1

Using Earth’s resources; pot. water

Mark Scheme 1

Level GCSE (9-1)

Subject Chemistry

Exam Board AQA


Sub Topic Using Earth’s resources; pot. water

Difficulty level Silver Level

Booklet Mark Scheme - 1


Score: /55

Percentage: /100

Grade Boundaries:

A* A B C D E U

>85% 777.5% 70% 62.5% 57.5% 45% <45%



Page 2

M1.(a) filtration or by passing through filter beds to remove solids

1

sterilisation to kill microbes

allow chlorine / ozone allow ultraviolet light 1

(b) water needs more / different processes 1

because it contains any two from: • more organic matter • more microbes • toxic chemicals or detergents

2

(c) (as part of glassware attached to bung) salt solution in (conical) flask

allow suitable alternative equipment, eg boiling tube 1

(at end of delivery tube) pure water in test tube which must not be sealed

allow suitable alternative equipment, eg, beaker, condenser 1

heat source (to heat container holding salt solution) 1

if no other mark obtained allow for 1 mark suitable equipment



Page 3

drawn as part of glassware attached to bung and at end of delivery tube

(d) determine boiling point 1

should be at a fixed temperature 100°C

allow should be 100°C

allow if impure will boil at a temperature over 100°C 1

(e) high energy requirement 1

[11]



Page 4

M2.(a) filter 1

to remove solids or insoluble particles

OR

add coagulant (1)

flocculation / settling / remove solids (1) 1

(add) chlorine

accept ozone / UV 1

to reduce the number of microbes

accept to kill microbes / bacteria / germs

accept sterilise

allow disinfect

ignore remove microbes 1

(b) (i) ion exchange resin

allow ion exchange column

allow sodium ions / Na+

allow hydrogen ions / H+

1

(ii) prevent growth of microbes

accept sterilise

accept to kill microbes / bacteria / germs

accept to reduce the number of microbes

ignore remove microbes 1

(c) high cost of energy / heating

allow uses a lot of energy 1

(d) any one from: • helps to develop / maintain bones

allow any suitable positive effect on bones • helps to develop / maintain teeth

allow any suitable positive effect on teeth • reduces heart disease

1

[8]



Page 5

M3.(a) (i) distillation 1

(ii) 100 / one hundred 1

(b) (i) measuring cylinder or pipette or burette

allow phonetic spelling

do not accept teat pipette

ignore any additional words or volumes 1

(ii) (re)heat the evaporating basin

accept heat to constant mass for 2 marks 1

weigh (again) or mass will not change

if no other mark awarded allow 1 mark for a chemical test for water

1

(iii) 33.2 (g)

correct answer with or without working scores 2 marks

allow mass of residue = (24.04 g − 23.21 g) = 0.83 for 1 mark

allow ecf (mass of residue × 40) for 1 mark 2

(c) to kill microbes / bacteria or to sterilise / disinfect water

allow to prevent disease

ignore ‘to make it safe to drink’ 1



Page 6

(d) Marks awarded for this answer will be determined by the Quality of Communication (QoC) as well as the standard of the scientific response. Examiners should also refer to the information on page 4, and apply a ‘best−fit’ approach to the marking.

0 marks No relevant content

Level 1 (1 − 2 marks) A simple relevant comment has been made on the data from at least one of the graphs.

Level 2 (3 − 4 marks) At least two of the graphs have been considered with a relevant comment made.

Level 3 (5 − 6 marks) All the graphs have been considered and relevant comments made about each. A justified conclusion may be given.

examples of chemistry points made in the response:

extra information

• (graph 1 shows) fluoride ions reduce the amount of tooth decay • (graph 1 shows) the effect in reducing tooth decay is greatest for 55−64 year olds

accept any in range 55 − 64 • (graph 2 shows) the fluoride ions reduce percentage with decayed teeth • (graph 2 shows) effect is greatest at 2.5 to 3 mg per 1000 g of water then decay

increases if more than 2.5 to 3 mg of fluoride ions per 1000 g water

accept any in range 2.5 − 3 • (graph 2 shows percentage) decay decreases from 0 to 2.5 / 3 mg per 1000 g • (graph 3 shows) more marked / brittle teeth as fluoride level increases • above points linked together to draw a justified conclusion

6

[14]



Page 7

M4.(a) any two from:

• copper / ores are running out / harder to find

• there are no / very small amounts of high-grade copper ores left

• copper metal is in demand

• copper is expensive

• now economical to extract copper from low-grade ores

it = copper

allow new methods of extraction e.g. bioleaching and phytomining

allow high-grade ores are running out for 2 marks 2

(b) (i) large amounts / 98% of rock to dispose of as waste

accept contains toxic (metal) compounds / bioleacher

orwaste rock takes up a lot of space 1

(ii) (copper sulfide reacts with oxygen to) produce sulfur dioxide / SO2

allow (sulfur reacts with oxygen to) produce sulfur dioxide / SO2

1

that causes acid rain

allow description of effects of acid rain or sulfur dioxide

if no other mark awarded allow CO2 produced which causes global warming or CO2 produced by burning fuel or heating the furnace for 1 mark

1

(iii) any one from:

• large amounts of fuels / energy used (for the furnace and electrolysis)

allow large amounts of electricity needed

ignore high temperature / electrolysis unqualified

• (the extraction has) many steps / stages / processes

allow (extraction) is a long process / takes a lot of time



Page 8

• large amounts of ore / material have to be mined

allow ores contain a low percentage of copper 1

(iv) (copper ions move towards) the negative electrode / cathode 1

because copper ions / Cu2+ are positively charged or are oppositely charged or copper ions need to gain electrons

allow because metal ions are positive or opposites attract 1

(v) (growing) plants 1

[9]



Page 9

M5. (a) filtered: removes insoluble / solid

Ignore named substances / minerals

do not accept ions 1

chlorine: kills microorganisms / microbes / bacteria / disinfects (water)

allow kills germs / pathogens or sterilises

allow chlorine is a disinfectant

ignore cleans water or removes impurities / bacteria 1

(b) (i) advantages of portable:

accept converse throughout

any two from :

• costs less

• little training needed

• water can be tested within 10 seconds / immediately / quicker

• can be used anywhere 2

disadvantage of portable

less precise / sensitive

allow only detect down to 0.1 mg

ignore less accurate 1

(ii) (PIWE) is unbiased

it / they = PIWE

allow honest / trusted / respected / reliable

ignore professional / scientific / skilled

or



Page 10

company may be biased

allow company trying to sell products 1

[6]



Page 11

M6. (a) sterilise / disinfect (water)

ignore removes bacteria / impurities / disease

or

kill bacteria / micro-organisms / microbes / germs / pathogens

ignore cleans the water / makes (water) safe

allow destroy bacteria or gets rid of bacteria 1

(b) any two from:

ignore reference to safe / unsafe

• chlorine is toxic / poisonous

• so (too much) will be dangerous / harmful / kill people / cause illness / health problems

allow causes damage

• cause breathing difficulties or cause (more) allergic reactions / skin or eye irritation

• too little will not kill bacteria

allow bacteria still there 2

(c) cheap / easy / quick to use (process)

accept prevents typhoid / cholera

ignore reference to specialists or equipment 1

(d) (i) fair / more ideas / views / opinions or less chance of bias or more democratic

allow idea of different points of view / balanced view

allow avoids undue influence owtte 1

(ii) (more likely) to have support / influence / convince people

ignore well respected



Page 12

allow ideas about trust eg people will have more confidence in their views / more likely to be believed

allow ideas about expertise eg more likely to know what they are talking about / have done experiments / tests

allow have knowledge / understanding

allow (more) reliable 1

(iii) (more likely) to be correct / less likely to be incorrect

owtte

or

reliable / factual / accurate / based on proof / based on experiments or tests / based on validation

ignore based on evidence unqualified

allow hearsay / opinion can be biased 1

[7]



Page 1

Life cycle assessment + recycling Mark Scheme

Level GCSE (9-1)

Subject Chemistry

Exam Board AQA


Sub Topic Life cycle assessment + recycling


Booklet Mark Scheme


Score: /42

Percentage: /100

Grade Boundaries:

A* A B C D E U

>85% 777.5% 70% 62.5% 57.5% 45% <45%



Page 2

M1.(a) (i) central block 1

(ii) conducts electricity 1

(b) any two from: • visual pollution • noise pollution • dust pollution • habitat destruction.

2

(c) (i) to concentrate the ore / copper carbonate or to remove / separate the rock

1

(ii) 12 (tonnes)

If answer is incorrect allow one mark for (127 + 132) − 247 or

259 - 247 2

(iii) any one from: • so no reactant is wasted / left unreacted • so they know how much product they will make • need to record / compensate for the carbon dioxide produced

allow so they can work out their carbon footprint. 1

[8]



Page 3

M2. (a) atoms 1

(b) mixture 1

metal 1

structure 1

smart 1

(c) (i) any two from:

• saves raw materials / iron ore

• saves energy / fuels

accept cheaper / saves money

• make new / useful items

• make money / it is economic

• reduces pollution

allow less harmful for the environment

• decreases cost of steel cans

• reduces carbon dioxide emissions

• decreases waste materials / use of landfill 2



Page 4

(ii) any one from:

• provide information / education of the need to recycle

• legislate against / charge for waste

• reward / pay people to recycle

accept fine people for not recycling

• put labels on the cans

• provide recycling bags / bins / areas 1

[8]



Page 5

M3. (a) (i) C2H4

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 6

M4. (a) (i) monomers 1

(ii) crude oil 1

(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]



Page 7

M5. (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 8

M6. (a) (i) poly(ethene)

accept polythene 1

(ii) cracking 1

(iii) hydrogen 1

(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



Page 9

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 1

Life cycle assessment + recycling Mark Scheme 1

Level GCSE (9-1)

Subject Chemistry

Exam Board AQA






Score: /56

Percentage: /100

Grade Boundaries:

A* A B C D E U

>85% 777.5% 70% 62.5% 57.5% 45% <45%



Page 2

M1.(a) all points correct

±1 small square

allow 1 mark for 6 or 7 plots 2

Year Percentage (%) of

bottles made from other materials

1975 5

1980 10

1985 22

1990 42

1995 70

2000 72

2005 90

2010 95

1

(b) Level 3 (5–6 marks): A detailed and coherent argument is provided which considers a range of issues and comes to a conclusion consistent with the reasoning.

Level 2 (3–4 marks): An attempt to describe the advantages and disadvantages of the production and uses is made, which comes to a conclusion. The logic may be inconsistent at times but builds towards a coherent argument.

Level 1 (1–2 marks): Simple statements made. The logic may be unclear and the conclusion, if present, may not be consistent with the reasoning.

0 marks: No relevant content.

Indicative content

• glass – 2 stages in production of soda-lime glass • glass – second stage, heating sand, limestone and sodium carbonate • HDPE – 3 stages in production • HDPE – second stage, cracking of naphtha to obtain ethene • HDPE – third stage, polymerisation of ethene • fewer stages in glass production, may be quicker



Page 3

• higher temperature in glass manufacture, therefore maybe higher energy requirement

• glass bottle can be reused • consideration of collection / cleaning costs to reuse glass bottles • other glass products can be made from recycled glass • plastic has greater range of sizes • both produced from limited raw materials • higher percentage recycled materials in glass conserves raw materials

This indicative content is not exhaustive, other creditworthy responses should be awarded marks as appropriate.

6

[9]



Page 4

M2. (a) (i) reduction

accept redox / smelting 1

(ii) 3 4 3 1

(b) (i) 55

ignore other units

(ii) Water

accept sodium hydroxide

accept correct formulae H2O or NaOH 1

(iii) any one from:

• save energy / fuel for transporting the ore

accept less (cost of) transport allow transported quickly

• (old) quarries nearby for waste/red mud 1

(c) Environmental

any one from:

• less mining / quarrying (of bauxite)

allow loss of habitat / less qualified noise pollution

• less landfill space needed / used

allow less red mud / waste

• less use of fossil fuels / energy

• less carbon dioxide produced 1



Page 5

Ethical or social

any one from:

• saves resources

allow using resources more than once

• creates (local) employment

if answers reversed and both correct award 1 mark

• more people aware of the need for recycling

allow less qualified noise pollution if not given in environmental 1

[7]



Page 6

M3. (a) (i) low percentage / very little of metal (in the ore)

accept only 0.5% metal in the ore or over 99% waste in the ore or nearly 100% waste in the ore

ignore reference to percentage of metal in the Earth's crust or energy used or pollution

1

(ii) any one from

(it = iron)

• iron uses less energy / fuel for extraction

ignore electrolysis / uses electricity / reactivity

• iron has more uses

• more demand for iron

ignore high abundance in the Earth’s crust / high percentage of metal in ore

• iron is stronger

ignore harder

• cheaper / costs less

• easier to extract 1

(b) (i) has melting point lower than 950°C

(it = aluminium)

allow has a low melting point

ignore boiling point 1

(ii) electrode(s) made of carbon 1

oxygen reacts with electrode(s) / carbon

accept C + O2 (→ CO2)



Page 7

NB oxygen reacts with the carbon electrode(s) = 2 marks 1

(iii) any two from:

• saves resources / non-renewable

accept aluminium / ore will run out or conserves aluminium

• landfill problem

accept aluminium does not corrode

• saves energy / fuel / electricity

ignore global warming

• less carbon dioxide / carbon emissions or reduces carbon footprint

ignore consequences of quarrying / mining

• less quarrying / mining

ignore pollution / harms environment / costs / easy to recycle 2

[7]



Page 8

M4. (a) (i) C

must be correct symbol

do not accept carbon

any balancing must be correct 1

(ii) Fe + CO2

correct formulae 1

2... . + 3... .

correct balancing

allow Fe2 + 3CO2 for this mark 1

(iii) layers / atoms in pure iron are able to slide over each other

it = pure iron

accept ions for atoms

ignore molecules / particles

or

layers / atoms in cast iron are unable to slide over each other (easily) 1

(b) any three from:

mention of ozone = max 2

• less iron ore used

accept the idea that ores would be conserved but not unspecified conservation

• less other metals extracted / used to make different steels

accept the idea that ores would be conserved but not unspecified conservation

• less fuel used

accept the idea that fuels would be conserved



Page 9

ignore reduces energy requirements

• less specified pollution

accept global warming / greenhouse effect / CO2 / CO / carbon emissions / acid rain / SO2 / global dimming /

do not accept ozone layer

• less / no landfill space needed

ignore reduces waste

• less / no mining needed or fewer specified effects of mining

accept effect such as eyesore / loss of habitat

eg ‘less mining iron ore’ = 2 marks 3

[7]



Page 10

M5. (a) (i) polyethene / poly(ethene)

accept polythene / polyethylene 1

(ii) needs heat / energy / high temperature / fuel (for cracking)

ignore other processes 1

produces carbon dioxide / CO2

ignore use of CO2 or ‘produces carbon’ 1

(b) any three from:

• use water from local sources or water from close to home

• recycle bottles in the UK / close to home

accept do not recycle in other countries / Asia

• (reduction in distance travelled) would reduce CO2 emitted by transport

accept use of transport with low / no carbon dioxide emissions

• use tap water

• use glass bottles / waxed cartons / metal bottles

do not accept ‘do not use plastic bottles’ without an alternative material

• do not put in landfill or recycle more

• reuse / refill plastic bottles

• tax imported water / plastic bottles (to offset carbon cost)

• make more / all plastic bottles in UK

answers must be about the reduction of carbon cost 3

[6]



Page 11

M6. (a) (i) reacts with carbon / C

accept burns / oxidises carbon 1

carbon dioxide / CO2 / gas is formed / given off

accept carbon monoxide / CO

accept correctly balanced equation for 2 marks

ignore state symbols 1

(ii) change / improve properties

accept any specific property

accept to make alloys / special steels

ignore brittle 1

(b) any two from:

• to conserve ores / iron

accept ores / iron are non-renewable / non-sustainable allow less quarrying / mining

• to prevent the use of landfills

allow reduce waste

• to conserve energy / fuel

accept fossil fuels are non-renewable

• to reduce carbon / carbon dioxide emissions

• to meet EU / International targets

ignore costs / demand 2

[5]



Page 12

M7. (a) any three from:

• resources / aluminium / ores are conserved

accept converse argument

• less / no mining or less associated environmental problems eg quarrying / eyesore / dust / traffic / noise / loss of land / habitat

ignore just pollution

• less / no waste (rock) / landfill

do not accept ‘wastes 50% of the ore’

• no purification / separation (of aluminium oxide)

• (aluminium extraction / production) has high energy / electricity / heat / temperature requirements

• less carbon dioxide produced

accept no carbon dioxide produced

ignore references to cost 3

(b) statement

ignore density 1

linked reason

eg (pure) Al / it is weak / soft (1)

as layers / rows can slide (over each other) (1)

or

alloy / other metals / they make it stronger / harder (1)

stops layers / rows sliding over each other (1)

accept disrupts the structure owtte if no other mark awarded

accept to form an alloy or to change properties for 1 mark 1

[5]



Page 13

M8. (a) (i) contain enough metal to make it economical / worth while to extract 1

(ii) reduction

accept displacement

accept redox 1

(iii) Fe + CO2

do not accept Fe2 / Fe4

1

correct balancing

accept multiples and halves

2Fe2O3 + 3C → 4Fe + 3CO2

allow Fe2 / Fe4 as ecf 1

(b) Pure Iron

(in pure metal all the atoms are the same size and) able to slip / slide over each other – (property soft)

OWTTE ignore references to molecules / particles

if they say ‘move’ both times, allow one mark but ‘crack’ or ‘split’ is wrong..

1

Cast iron

(in cast iron) different sized atoms / larger atoms or structure is distorted / disrupted

OWTTE 1

so it is difficult for layers of atoms to slip / slide over each other

OWTTE 1

(c) any three from:

• conserves / saves resources / metal ores

• saves energy resources (used for extraction / processing)

accept cheaper / saves money



Page 14

• decreases waste materials

• decreases a named pollution

do not accept acid rain 3

[10]



Page 1

Life cycle assessment + recycling Mark Scheme

Level GCSE (9-1)

Subject Chemistry

Exam Board AQA



Difficulty level Gold Level

Booklet Mark Scheme


Score: /23

Percentage: /100

Grade Boundaries:

A* A B C D E U

>85% 777.5% 70% 62.5% 57.5% 45% <45%



Page 2

M1. (a) allow answers referring specifically to the naphtha fraction

crude oil is evaporated/vaporised (by heating) 1

the vapours are condensed (by cooling) 1

(fractions condense) / boil at different temperatures

allow fractions have different boiling points 1

(b) any four from:

answer yes or no does not gain credit

ignore references to volume of milk held / number of bottles used / biodegradability / habitats / pollution / mining / dust

each marking point must be a comparison

milk bag points

• uses (75%) less crude oil to make (than a plastic milk bottle)

allow eg uses 75% less

poly(ethene) which is made from crude oil

• uses less energy / fuel to make (than a plastic / glass milk bottle)

• produces less carbon dioxide to manufacture (than a plastic / glass milk bottle)

allow produces less greenhouse gases / causes less global warming

allow produces less CO2 on burning

• produces less waste (than a plastic / glass milk bottle)

allow takes up less landfill (space)

allow an argued case for more waste eg milk bags are discarded / cannot be reused



Page 3

• less fuel used for transport than glass milk bottles

• (produces waste because) milk bags are only used once whereas glass bottles can be re-used

allow milk bags are discarded but glass bottles can be reused (24 / many times)

allow glass bottles can be reused but milk bags can’t

poly(ethene) points

• uses a limited raw material / crude oil whereas the raw materials for glass are almost unlimited

• less (5%) poly(ethene) is recycled (compared to glass (35%))

allow (35%) glass is recycled or (5%) poly(ethene) (bottles) recycled BUT milk bags aren’t / are discarded

or

recycled poly(ethene) is not used to make new bags whereas recycled glass is used to make new bottles

4

[7]



Page 4

M2. Reused

• saves raw materials / crude oil

• unable to reuse many times

• bags easily split

• saves energy / fuel / transport

• fewer bags needed / made

• reduces carbon / CO2 emissions

• reduces use of landfill

• saves cost of a new bag

• no waste 1

Recycled


• has to be collected / transported / washed / separated / melted

• saves energy / use of fuel

• reduces carbon / CO2 emissions


• can be used for new products

ignore uses energy 1

Burned

• heat / energy released can be used (for heating / generating electricity)

• has to be collected / transported


• wastes the resource / plastic

• releases harmful gases / toxic gases / CO2

1



Page 5

Dumped

• collected / transported with household waste

• wastes the resource

• plastic uses landfill

• (slowly) biodegrades or produces methane which can be used as a fuel

• produces methane which is a greenhouse gas / could cause explosions

• (not biodegradable so) does not release CO2 / green house gas into the air

• not biodegradable / take years to decompose

ignore cost / litter / waste / global warming / habitats unless mentioned above 1

[4]



Page 6

M3. (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) C10H22 → C6H14 + 2C2H4

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 / CnH2n+2

or ethene is an alkene / CnH2n

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



Page 7

(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

environmental argument against recycling

any one from:

• uses (fossil) fuels that are non-renewable / form CO2 / CO / SO2 / NOx / 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 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



Page 8

• more jobs / employment for people 2

[12]



Page 1

Using materials Mark Scheme 1

Level GCSE (9-1)

Subject Chemistry

Exam Board AQA


Sub Topic Using materials




Score: /58

Percentage: /100

Grade Boundaries:

A* A B C D E U

>85% 777.5% 70% 62.5% 57.5% 45% <45%



Page 2

M1.(a) Air 2

Steel 1

(b)

Allow 1 mark for the correct meanings linked to context but incorrect way around 1

1

(c) Damp litmus paper turns white 1

(d) Iron(III) 1

[6]



Page 3

M2.(a) 50 1

(b) 5% 1

(c) any two from:

• cost (9 carat is cheaper) • pure gold is soft or 24 carat gold is soft or 9 carat gold is harder

allow 9 carat gold is stronger

allow gold is an alloy in 9 carat gold • can change the colour

2

[4]



Page 4

M3.(a) sodium loses (electron)

sharing / covalent / metallic = max 2 1

chlorine gains (electron) 1

1 or an (electron) 1

(b) (i) Have no overall electric charge 1

(ii) Should iodine be added to salt? 1

reason any one from: • cannot be done by experiment

accept difficult to get / not enough evidence • based on opinion / view

allow must be done by survey • ethical or economic issue.

1

(c) (i) nitric (acid) 1

(ii) an alkali 1

(iii) indicator

accept any named acid base indicator 1

(d) (i) Crystallisation 1

(ii) fertiliser

allow to help crops grow 1



Page 5

(iii) any one from: • pressure

allow concentration • temperature

ignore heat • catalyst.

1

[12]



Page 6

M4.(a) alloy 1

(b) in mixture:

different sized / bigger atoms 1

so there are no layers / rows / lines (to slide)

accept converse 1

(c) any two from:

ignore references to bend and mould

• cost • toxicity • strength • appearance of brace • unreactive or resistant to corrosion / saliva

allow rusting as alternative to corrosion 2

(d) crosslinks

allow lines / bonds between the rows / chains 1

[6]



Page 7

M5.(a) (i) an alloy 1

(ii) harder 1

(b) (i) 162.5

correct answer with or without working gains 2 marks

if no answer or incorrect answer then evidence of correct working [56 + (3x35.5)] gains 1 mark

2

(ii) 34.46

accept rounding from 34 - 34.5


accept ecf from (b)(i) correctly calculated for 2 marks

if no answer or incorrect answer then evidence of 56 / 162.5 or 56 / answer to (b)(i) gains 1 mark

2

[6]



Page 8

M6. (a) +1/+

do not accept 1 without the + 1

electron

allow phonetic spelling 1

(b) (i) elements 1

(ii) non-metal 1

(c) soft 1

an alloy 1

(d)



Page 9

one mark for each correct link

extra lines lose the mark 3

[9]



Page 10

M7. (a) (i) 2.5(kg)

ignore units 1

(ii) 40% (cement) and Test 3

ignore units 1

because it is anomalous or because it is much lower than the other two readings

accept value not used to calculate mean

ignore outlier 1

(iii) as the percentage of cement increases the mass needed to break the sleeper increases

allow ‘strength’ for ‘mass needed’

allow correct relationship using percentage of sand 1

(iv) volume/percentage / amount of water

accept temperature 1

(b) any two from:

• availability (of the raw materials)

• cost of the raw materials

• purity (of the raw materials) 2

[7]



Page 11

M8. (a) 79 1

79 1

(b) hundred 1

(c) (i) electron(s) 1

(ii) three 1

(d) changes rate of reaction

accept lowers activation energy

or

speeds up / slows down reaction

accept reduces costs 1

(e) (i) melt 1

(ii) crosslinking

allow answers on diagram



Page 12

or

(covalent) bonds between polymers / chains

allow bonds between layers do not allow intermolecular

1

[8]



Page 1

Using materials Mark Scheme 1

Level GCSE (9-1)

Subject Chemistry

Exam Board AQA






Score: /51

Percentage: /100

Grade Boundaries:

A* A B C D E U

>85% 777.5% 70% 62.5% 57.5% 45% <45%



Page 2

M1.(a) all points correct

±1 small square

allow 1 mark for 6 or 7 plots 2

Year Percentage (%) of

bottles made from other materials

1975 5

1980 10

1985 22

1990 42

1995 70

2000 72

2005 90

2010 95

1

(b) Level 3 (5–6 marks): A detailed and coherent argument is provided which considers a range of issues and comes to a conclusion consistent with the reasoning.

Level 2 (3–4 marks): An attempt to describe the advantages and disadvantages of the production and uses is made, which comes to a conclusion. The logic may be inconsistent at times but builds towards a coherent argument.

Level 1 (1–2 marks): Simple statements made. The logic may be unclear and the conclusion, if present, may not be consistent with the reasoning.

0 marks: No relevant content.

Indicative content

• glass – 2 stages in production of soda-lime glass • glass – second stage, heating sand, limestone and sodium carbonate • HDPE – 3 stages in production • HDPE – second stage, cracking of naphtha to obtain ethene • HDPE – third stage, polymerisation of ethene • fewer stages in glass production, may be quicker • higher temperature in glass manufacture, therefore maybe higher energy

requirement



Page 3

• glass bottle can be reused • consideration of collection / cleaning costs to reuse glass bottles • other glass products can be made from recycled glass • plastic has greater range of sizes • both produced from limited raw materials • higher percentage recycled materials in glass conserves raw materials

This indicative content is not exhaustive, other creditworthy responses should be awarded marks as appropriate.

6

[9]



Page 4

M2.(a) giant structure / lattice / layers / close packed

first 3 marks can be obtained from a suitably labelled diagram

incorrect structure or bonding or particle = max 3 1

made up of atoms / positive ions 1

with delocalized / free electrons 1

so electrons can move / flow through the metal

accept so electrons can carry charge through the metal

accept so electrons can form a current 1

(b) an alloy (is a metal which) has different types / sizes of atoms

accept converse for pure metal throughout

both marks can be obtained from suitable diagrams

allow made of different metals

allow mixture of metals / atoms / elements

ignore particles

ignore properties

do not accept compound 1

alloy has distorted layers

allow layers are unable to slide 1

(c) (i) can return to its original shape

accept shape memory alloy

accept smart alloy

ignore other properties 1

(ii) (pure copper is too) soft

accept converse

accept malleable or bends

accept copper is running out

ignore references to strength and weakness 1



Page 5

(iii) aluminium oxide

accept alumina

accept Al2O3

ignore bauxite / aluminium ore 1

(iv) any one from: • different conditions • different catalyst • different pressure

allow different concentration • different temperature.

do not accept different monomers 1

(d) any two from: • accurate • sensitive • rapid • small sample.

both needed for 1 mark 1

[11]



Page 6

M3.(a) (Chromium =) 20

in correct order 1

(Nickel =) 8

accept Chromium = 8 and Nickel = 20 for 1 mark 1

(b) (i) (because iron is made up of only) one type of atom 1

(ii) not strong

allow too soft or too flexible

accept it rusts / corrodes or that it could wear away

accept could change shape / bend

accept layers / atoms could slide (over each other) 1

(iii) structure is different / distorted / disrupted

accept not in layers or not regular 1

so it is difficult for layers / atoms / particles to slip / slide (over each other)

accept layers cannot slip / slide 1

[6]



Page 7

M4.(a) (alloy) atoms / ions / particles not in layers

accept layers are distorted

accept different (size) particles / atoms 1

so, (alloy) layers / atoms / ions / particles can’t slide

if no other mark awarded allow (an alloy) is a mixture of metals for 1 mark

1

(b) diamonds have a giant covalent structure 1

diamonds have strong bonds between carbon atoms 1

(c) (i) a compound 1

(ii) CH4

1

(iii) covalent 1

(d) methane has a low boiling point or boiling point less than 20°C molecules

1

because it has small molecules

accept it has forces between molecules



Page 8

accept weak forces between molecules for 2 marks 1

[9]



Page 9

M5. (a) 2,4

allow electrons in any position on correct shells 1

(b) (electron) 79 1

neutron

allow phonetic spelling 1

118 1

(c) (i) 16 and 9

in this order 1

(ii) any two from:

ignore reasons about colour / lustre / corrosion / rarity

• (100% / pure) gold is soft

allow layers can slide in pure gold

• (alloyed) to make the metal hard(er)

ignore just ‘the ring is an alloy’

allow (alloyed) to stop the layers sliding

allow (alloyed) to make the metal strong

• gold is expensive or alloy is less expensive 2

[7]



Page 10

M6. (a) 2.5


if answer incorrect

2.6 / 2.625 / 2.62 / 2.63

or recognise 3.0 as anomalous gains 1 mark

accept answer in table

ignore units 2

(b) as the percentage of cement increases the mass needed to break the sleeper increases

allow 50% cement is the strongest or 30% sand is the strongest or the highest amount of cement is the strongest

or

as the percentage of sand increases the mass needed to break the sleeper decreases

1

(c) (i) any two from:

• availability of materials

• cost (of materials)

• time needed (for the concrete mixture) to set/harden

• compression strength (of the concrete)

accept weight of the train

• testing full size (concrete railway sleepers)

accept any test on full size sleepers

accept ‘how well it would last / weather’ 2

(ii) any four from:

maximum of 3 marks if no comparison made

ignore yes or no

negative concrete:



Page 11

allow converse statements for wood

• more fossil fuel / energy / heat (needed to produce cement / concrete)

• cement / concrete resources / limestone not renewable whereas wood is renewable

• quarrying limestone destroys landscapes / habitats whereas growing wood improves landscapes / habitats

allow quarrying causes noise pollution / dust / etc.

• making cement / concrete releases carbon dioxide / greenhouse gases whereas growing wood absorbs carbon dioxide / greenhouse gases / is carbon neutral

allow making cement / concrete

causes global warming / climate

change whereas growing wood

reduces global warming / climate change

ignore loss of trees / deforestation (and resultant effects such as an increase in CO2)

positive concrete:

• (less resources are needed because) cement / concrete sleepers last longer or wood rots / needs replacing

ignore strength / ease of breaking

ignore weathering / effects of acid rain 4

[9]



Page 1

Using materials Mark Scheme

Level GCSE (9-1)

Subject Chemistry

Exam Board AQA




Booklet Mark Scheme


Score: /31

Percentage: /100

Grade Boundaries:

A* A B C D E U

>85% 777.5% 70% 62.5% 57.5% 45% <45%



Page 2

M1.(a) The ore is not pure or contains impurities or the ore does not contain 100% of the metal compound

allow to concentrate the metal or metal compound 1

rock / other compounds need to be removed / separated 1

(b) (i) (cast iron is) brittle

allow not strong

ignore weak 1

(ii) the oxygen reacts with carbon

allow carbon burns in oxygen or is oxidised 1

reducing the percentage of carbon in the mixture or producing carbon dioxide

1

(c) (i) aluminium has a low density 1

(ii) (because copper) is in the central / middle (block of the periodic table) 1

whereas aluminium is in Group 3 (of the periodic table) 1

(iii) iron is more reactive (than copper)

ignore cost 1

so copper is displaced / reduced 1

[10]



Page 3

M2.(a) because atoms / ions / particles in alloy are different (sizes)

do not allow reference to molecules

ignore reference to compounds 1

so layers distorted

(and layers / atoms / ions / particles) don’t slide or slide less easily

accept all marking points in a suitably labelled or annotated diagram

1

if no other mark awarded accept an alloy is a mixture or contains different metals / elements for 1 mark

1

(b) giant structure or lattice or macromolecule

max 3 marks if incorrect bonding 1

strong bonds (between carbon / atoms) 1

covalent (bonds) 1

each carbon / atom forms 4 bonds

accept tetrahedral

if no other marks awarded, allow carbon (atoms) for 1 mark 1

(c) reference to incorrect bonding = max 3 reference to ‘weak covalent bonds’ = max 2 allow correctly drawn diagram for first two marking points eg. (tangled) lines with no cross-links



Page 4

chains or large molecules

ignore layers 1

with intermolecular forces or forces between chains

allow bonds for forces accept no cross-links 1

that are weak

must relate to 2 nd marking point 1

and are easily overcome/ broken (when heated)

accept molecules / chains can flow / move 1

[11]



Page 5

M3. (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

(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



Page 6

• 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]



Page 1

Haber process + use of NPK fertilisers

Mark Scheme

Level GCSE (9-1)

Subject Chemistry

Exam Board AQA


Sub Topic Haber process + use of NPK fertilisers


Booklet Mark Scheme


Score: /52

Percentage: /100

Grade Boundaries:

A* A B C D E U

>85% 777.5% 70% 62.5% 57.5% 45% <45%



Page 2

M1.(a) sodium loses (electron)

sharing / covalent / metallic = max 2 1

chlorine gains (electron) 1

1 or an (electron) 1

(b) (i) Have no overall electric charge 1

(ii) Should iodine be added to salt? 1

reason any one from: • cannot be done by experiment

accept difficult to get / not enough evidence • based on opinion / view

allow must be done by survey • ethical or economic issue.

1

(c) (i) nitric (acid) 1

(ii) an alkali 1

(iii) indicator

accept any named acid base indicator 1

(d) (i) Crystallisation 1

(ii) fertiliser

allow to help crops grow 1



Page 3

(iii) any one from: • pressure

allow concentration • temperature

ignore heat • catalyst.

1

[12]



Page 4

M2.(a) natural gas

allow correct answer shown in box if answer line blank 1

(b) (i) 450


(ii) iron


(iii) The catalyst lowers the activation energy. 1

(c) (the gases are) cooled 1

ammonia condenses

allow ammonia liquefies 1

nitrogen and hydrogen are recycled

if no other mark awarded allow ammonia is separated for 1 mark 1

[7]



Page 5

M3. (a) (i) 10 1

(ii) OH-

1

(b) (i) air 1

(ii) particles move faster 1

particles collide more often 1

(iii) catalyst(s) 1

(c) liquid 1

[7]



Page 6

M4. (a) increases 1

(b) the reaction is reversible 1

(c) A liquid 1

(d) recycled / reused (owtte)

accept returned to pump / start 1

[4]

M5. (a) pressure 1

(b) nitrogen 1

hydrogen 1

(c) cooled 1

[4]



Page 7

M6. (a) (i) nitrogen + hydrogen → ammonia

accept full correct balanced equation 1

(ii) reversible (reaction) (owtte)

do not allow just ‘backwards’ (unqualified) 1

(iii) catalyst / speed up reaction

accept to lower activation energy 1

(iv) boiling point 1

(v) recycled (owtte) 1

(b) (i) used to make explosives (owtte) used to make medicines (owtte) 1

(ii) used to make fertilisers (owtte) 1

(c) (i) sensible answers such as

provides workers (owtte)

good transport links

ignore reference to raw materials 1

(ii) sensible idea 1

linked reason

idea

linked reason

eg escape of chemicals /fumes /waste gases / pollution

harmful to health / environmental damage owtte

do not allow harmful / damage / smell (unqualified)



Page 8

risk of explosion

because of high pressures / may endanger local people / dangerous

risk of fire

because of high temperatures / may endanger local people

noise

any detrimental effect on quality of life or night and day

lorries / traffic

danger / noise / pollution etc

unsightly

detrimental effect on quality of life / house prices / reduced tourism

uses a lot of land

loss of habitats 1

[10]



Page 9

M7. (i) potassium hydroxide

accept correct formulae 1

water 1

(ii) fertiliser 1

(iii) H+

accept hydrogen but not H 1

[4]

M8. (a) put on soil or for plants

accept land or field or garden or crops or plants

accept alternative answer to provide more food for increased population

for growth

accept to improve plant yield or help them grow

accept to replace or add nutrients (not nitrates) or minerals or to make plants grow better or for healthy plants

do not accept to make soil fertile or to feed plants 2

(b) (i) 2 1

(ii) 80 1

[4]



Page 1


Mark Scheme 1

Level GCSE (9-1)

Subject Chemistry

Exam Board AQA






Score: /57

Percentage: /100

Grade Boundaries:

A* A B C D E U

>85% 777.5% 70% 62.5% 57.5% 45% <45%



Page 2

M1. (a) Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response.Examiners should

also apply a �best-fit� approach to the marking.

0 marks

No relevant content.

Level 1 (1-2 marks) There is a simple description of a laboratory procedure for obtaining potassium chloride.

Level 2 (3-4 marks) There is a clear description of a laboratory procedure for obtaining potassium chloride from potassium hydroxide solution and hydrochloric acid that does not necessarily allow the procedure to be completed successfully by another person. The answer must include the use of an indicator or a method of obtaining crystals.

Level 3 (5-6 marks) There is a detailed description of a laboratory procedure for obtaining potassium chloride from potassium hydroxide solution and hydrochloric acid that can be followed by another person. The answer must include the use of an indicator and a method of obtaining crystals.

examples of the chemistry/social points made in the response:

• One reagent in beaker (or similar)

• Add (any named) indicator

• Add other reagent

• Swirl or mix

• Add dropwise near end point

• Stop addition at change of indicator colour

• Note volume of reagent added

• Repeat without indicator, adding same volume of reagent or remove indicator using charcoal

• Pour solution into basin / dish

• Heat (using Bunsen burner)

• Leave to crystallise / leave for water to evaporate / boil off water

Accept any answers based on titration 6



Page 3

(b) nitric (acid)

allow HNO3

ignore incorrect formula 1

(c) (i) because it is a fertiliser / helps plants grow

allow plant food

do not accept pesticide / herbicide / neutralising soil 1

(ii) tick by: ‘Should farmers stop using ammonium nitrate on their land?’ 1

any two from:

• cannot be done by experiment

accept difficult to get / not enough evidence

• based on opinion / view

allow must be done by survey

• ethical or economic issue

if top box ticked allow 1 mark for drinking water varies from place to place

2

[11]



Page 4

M2. (a) to speed up the reaction or it is a catalyst

allow higher level answers such as to reduce the activation energy

ignore cost or yield 1

(b) (i) reaction is exothermic

accept reverse reaction is endothermic or high temperature causes decomposition of ammonia

ignore reference to rate 1

(ii) more (gaseous) reactant molecules than (gaseous) product molecules

accept 4 volumes / moles of reactant and 2 volumes / moles of product

accept lower volume of products or volume lower on right hand side

accept ‘favours the reaction which produces fewer molecules’

ignore incorrect number of moles

ignore reference to ‘amount’ of product / reactant

ignore references to rate 1

(c) (rate is) too slow / slower owtte

allow catalyst would not work

accept at higher temperature the rate is quicker

accept at lower temperatures particles do not collide as often or fewer particles have the activation energy or particles do not have the activation energy

ignore reaction would not work

ignore optimum / compromise type answers 1

(d) cooled

allow ammonia / it is turned into a liquid or is condensed

ignore references to boiling point 1

[5]



Page 5

M3. (a) H+(aq) + OH– (aq) → H2O(l) or

H3O+(aq) + OH–(aq) → H2O(l)

mark for correct equation mark for state symbols any other symbols = 0 marks accept correct spectator ions e.g. Na+(aq) + OH– (aq) + H+(aq) + Cl– (aq) → Na+(aq) + Cl– (aq)

+ H2O(l) 2

(b) (i) nitric acid and ammonia (solution) HNO3 NH3 / NH4OH

mark for both accept ammonium hydroxide / NH4OH instead of ammonia

do not accept ammonia hydroxide do not accept hydrogen nitrate solution

accept correct formulae 1

(ii) provides oxygen or oxidising (agent) or oxidant

do not accept it contains oxygen alone or rich in oxygen

1

[4]



Page 6

M4. (a) nitrogen

consider answers as a list 1

hydrogen 1

(b) speed up the reaction

accept increase rate of reaction 1

(c) fertiliser

accept to replace or add nitrogen or nutrients

do not accept minerals or nitrates 1

growth

accept for protein or increased yield 1

[5]



Page 7

M5. (a) (i) fertilisers

for 1 mark 1

(ii) 7

for 1 mark 1

(iii) 5

for 1 mark (ignore other units)

1

(b) (i) both nitrogen and hydrogen

for 1 mark 1

(ii) two of: nitrogen; hydrogen/methane/natural gas; oxygen/air; water; any fuel (allow symbols, do not allow nitrogen oxides)

any two for 1 mark each 2

(c) (i) alkali/alkaline/base/basic

for 1 mark 1

(ii) must be nitrate

for 1 mark 1

(iii) thermometer or any other temperature measuring device

for 1 mark 1

[9]



Page 8

M6. (i) A = air B = natural gas

for 1 mark each 2

(ii) nitrogen

both for 1 mark 1

(iii) catalyst / speed up reaction

for 1 mark 1

(iv) recycle unreacted gases / save money

for 1 mark 1

[5]



Page 9

M7. (a)

the answer yes or no does not gain a mark

Yes – plants will grow faster

do not accept grow better 1

more food available, greater yield 1

OR

No – plants still grow without adding nitrates

accept the idea that small amounts of nitrate could be used 1

(nitrates) can ‘kill’ babies / causes brain damage

do not accept can stop respiration in babies 1

(b) (i) 2

accept two 1

(ii) 2 × 14 + 4 × 1 + 3 × 16 1

= 80 1

% 1

allow 1 mark for correct working for percentage 28/Y × 100, where Y is an incorrect formula mass allow 2 marks for formula mass of 80 where no working or correct working is shown allow 3 marks for 35 where no working or correct working is shown

[6]



Page 10

M8. (a) as a catalyst

accept to speed up the reaction (equilibrium) 1

(b) nitrogen + hydrogen ammonia

N2 + H2 NH3

accept mixed formula / word equations ignore balancing

1

(c) (i) the reaction is reversible / an equilibrium

accept that ammonia can break down again into nitrogen and hydrogen accept reaction goes both ways do not accept some nitrogen and hydrogen do not react

1

(ii) (the gases are cooled)

no marks as given in the diagram accept correct formulae NH3, N2 H2

1

ammonia removed as a liquid

accept ammonia liquefies or condenses

nitrogen and hydrogen are recycled

accept nitrogen and hydrogen are put back through the converter accept ‘other gases’ only if ammonia identified for first mark

1

[5]



Page 11

M9. (a) ammonium nitrate

accept NH4NO3

do not accept ammonia nitrate 1

(b) different reactions need different catalysts 1

(c) they are used over and over again

accept they are reused accept they are not used up accept they are not changed recycling is neutral

1

(d) any two from

they speed up reactions

they reduce energy requirements

accept allow reactions to take place at a lower temperature

they reduce costs

accept make process more economic 2

(e) (high pressure) increases the frequency of collisions

accept more collisions move faster is neutral

1

this increases the rate of reaction

accept ‘more successful collisions’ for 2 marks 1

[7]



Page 1


Mark Scheme

Level GCSE (9-1)

Subject Chemistry

Exam Board AQA




Booklet Mark Scheme


Score: /60

Percentage: /100

Grade Boundaries:

A* A B C D E U

>85% 777.5% 70% 62.5% 57.5% 45% <45%



Page 2

M1. (a) (i) nitrogen - air

accept atmosphere 1

hydrogen - north sea gas / natural gas / methane / CH4

accept water / (crude) oil / coal / hydrocarbons / brine 1

(ii) allow converse throughout

• high temperature gives a low yield 1

• because reaction is exothermic

must be linked to first bullet point 1

• but at low temperatures the rate is (too) slow

if no other marks awarded accept 450°C is a compromise between yield and rate

or

450°C gives a reasonable yield in a reasonable time for 1 mark 1

(iii) nitric (acid)

accept HNO3 1

(b) Ammonia / Haber process can be used to make fertiliser 1



Page 3

with a specified economical reason eg raw materials for Haber process readily available eg transport costs are lower or no need to import eg Haber process is a continuous process

ignore employment / labour costs 1

[8]



Page 4

M2. (a) 2 marks for comments related to temperature

low / lower / lowest temperature (or 100 °C from graph)

ignore references to catalyst 1

any one from:

• (forward) reaction exothermic

or reverse reaction endothermic

• if the temperature is increased the yield of product will decrease or reaction right to left

high temperature favours reverse reaction or reverse argument

the lower the temperature the greater the yield = 2 marks

2 marks for comments related to pressure 1

high / higher / highest pressure (or greater than 200 atm. from graph) 1

any one from:

• four reactant molecules but only two product molecules (owtte)

reverse reaction goes from 2 molecules / moles / volumes to 4 molecules / moles / volumes

• increase in pressure favours the reaction which produces the least number of molecules

decrease in pressure favours the back reaction because it produces the most molecules

1

(b) any three from:

• at low temperatures the reaction is too slow

• 450 °C gives a reasonable yield at a fast rate / compromise between yield and rate (*)

• 200 atm. gives a reasonable yield at a reasonable cost / safely / compromise between yield and cost / safety (*)

(*) or 450°C and 200 atm / these are compromise conditions for 1 mark

• catalyst works better at higher temperature



Page 5

• (very) high pressures could be dangerous (owtte)

safety factor

• (very) high pressures are expensive (owtte)

• (yield is not too important because) unreacted gases can be recycled 3

[7]



Page 6

M3. (a) 16%

for 2 marks

(attempt by drawing lines etc gains 1 mark) 2

(b) iron is a catalyst; which speeds up the reaction

for 1 mark each 2

(c) (from the graph) the best yield is obtained at high pressure; and low temperature; it is a reversible reaction; in which formation of ammonia is favoured at low temperature (because) the reaction is exothermic; and the formation of ammonia is favoured at high pressure because greater number of gaseous reactant molecules than gaseous product molecules/because greater vol of reactant than volume of product molecules; pressure used is limited by cost/materials; rate of reaction slow at low temperatures; actual temperature and pressure used is a good compromise (between a good yield and reasonable rate); removal of ammonia makes rate more important than yield;

any 8 for 1 mark each 8

[12]



Page 7

M4. (a) (i) atmosphere

or (fractional distillation of liquid) air 1

(ii) either more (chance) of them colliding/

not just ‘faster’

coming into contact or the volume of the product / the ammonia is less than / only half the volume of the reactants / the nitrogen and hydrogen

1

(iii) 3 × (1 ×2) of hydrogen → 2 × (14 +1 ×3) of ammonia

accept 6 parts of hydrogen →34 parts of ammonia or similar

i.e. candidate uses the atomic masses and works correctly from the equation

1

= 225 (tonnes/t)

unit not required 1

(b) (i) megapascal(s)

accept million pascal(s) 1

(ii) 28 (%)

accept any answer in the range 28.0 to 28.5 inclusive 1

(iii) reduce the temperature and increase the pressure

both required 1

(iv) either use a catalyst

accept use iron as a catalyst

accept use iron which has been more finely divided



Page 8

accept use iron / catalyst with a bigger (surface) area

accept use a better catalyst 1

or remove the ammonia (as it is produced)

accept react the ammonia with or dissolve the ammonia in water (as it is produced)

1

(c) ammonia nitric acid phosphoric acid

all three on the left correct

ammonia potassium chloride

all three on the right correct

water or water vapour

accept ‘steam’ 1

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Page 9

M5. (a) any one from

(as a) catalyst

or to mix with promoters

to speed up the reaction (process)

or process is quicker do not credit just it is quicker

to save energy to reduce costs

or process is cheaper do not credit just it is cheaper

larger surface area (than lumps of iron)

or larger surface area for the (catalysed) reaction (to take place)

1

(b) (i) water or steam and methane or natural gas or North Sea gas

both required either order 1

(ii) EITHER more (chance) of them colliding / coming into contact

do not credit just faster

OR volume of the product / ammonia less than / only half the volume of the reactants / the nitrogen and hydrogen

1

(iii) EITHER 680 (tonnes)

OR 28 (of nitrogen) → 34 (of ammonia)

accept any correct 14 : 17 ratio 1

560 (of nitrogen) → 34 × 20 (of ammonia) 3

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Page 10

##

(a) N2 + 3 H2 ↔ 2 NH3

2

(b) (i) lower temperature gives higher % conversion higher pressure gives higher % conversion

each for 1 mark 2

(for T = 350 °C and P = 400 At. award 2 marks)

the most economical combination reaction too slow at lower temperatures plant too expensive at higher pressures

any 2 for 1 mark each 2

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Page 11

##

(a) rate of reaction is increased iron/powder acts as catalyst at higher temperatures at higher pressures

any 4 answers for 1 mark each 4

(b) yield of ammonia is increased at higher pressure since equilibrium is moved to the right (idea) but there is high cost in manufacturing the plant to withstand very high pressures so optimum* pressure of about 250 atmospheres is used (* – just quoting the figures not enough) very high pressure increases safety risk yield of ammonia is increased at lower temperatures since equilibrium is moved to the right but the rate of reaction is reduced at lower temperatures so process becomes uneconomic optimum temperature of about 450oC is used yield of ammonia is increased if the ammonia is removed from the reaction mixture

since equilibrium is moved to the right (idea) so ammonia is removed as a liquid after cooling and condensing unreacted nitrogen and hydrogen recycled

(credit nitrogen and ammonia because of misprint on the diagram)

NB Answers in (b) must clearly relate to yield not to rate (except for the qualification w.r.t. temperature)

any 7 points for 1 mark each 7

[11]


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