Life cycle assessment & recycling – GCSE Chemistry exam questions with mark scheme

1Grade 6–74 marks

A supermarket compares life-cycle assessments (LCAs) for a paper bag and a plastic (poly(ethene)) bag.

	Paper bag	Plastic bag
Raw material	wood	crude oil
Energy to make one bag in MJ	1.7	0.6
Mass of CO₂ released making one bag in g	110	40
Disposal	biodegradable; recycled easily	not biodegradable; can be reused many times

Evaluate the use of paper bags compared with plastic bags. Use the data in the table. [4]

any three from: (paper bag) made from a renewable resource (wood) whereas crude oil is finite / non-renewable; paper bag needs more energy to make (1.7 MJ vs 0.6 MJ / about 3 times as much); paper bag releases more CO₂ when made (110 g vs 40 g / about 3 times as much), so contributes more to global warming / climate change; paper bag is biodegradable / easily recycled whereas plastic bag is not biodegradable / persists in landfill / litter; plastic bag can be reused many times (so its impact per use is lower) — first point(1)
second point from the list above(1)
third point from the list above; at least one of the three points must quote or compare figures from the table, otherwise max 2 of these 3 marks(1)
a justified overall judgement (either bag may be preferred) consistent with the points made, e.g. plastic bags have lower production impact, especially if reused many times; or paper bags are better because they come from a renewable resource and are biodegradable despite higher energy use and CO₂; an unsupported conclusion does not score(1)
Answer: Paper: renewable and biodegradable but nearly 3× the energy and CO₂ per bag; plastic: finite raw material, persists in environment, but lower production impact and reusable — a justified conclusion is needed.
Examiner tip: 'Evaluate' needs a judgement at the end — listing points without a conclusion caps you at 3 marks.

2Grade 1–3Foundation3 marks

A company carries out a life cycle assessment (LCA) for an aluminium drinks can.

(a) Match each activity to the stage of the LCA it belongs to. Each stage is used once. [2]

Activity	Stage of LCA
Bauxite ore is mined from the ground	Disposal
Aluminium sheet is rolled and pressed into cans	Extracting and processing raw materials
The drink is kept cold in a fridge before it is drunk	Manufacturing and packaging
The empty can is put in a landfill site	Use and operation

(b) Some parts of an LCA are easy to measure.

Give one quantity that is easy to give a value to in an LCA. [1]

(a) two or three activities matched correctly; an activity matched to more than one stage scores no credit for that activity(1)
(a) all four activities matched correctly: mining bauxite → extracting and processing raw materials; rolling/pressing cans → manufacturing and packaging; keeping drink cold in a fridge → use and operation; landfill → disposal(1)
(b) any one from: (amount of) energy used; (volume of) water used; (mass of) raw materials / resources used; (amount of) waste produced; allow mass of carbon dioxide released; do not accept 'pollution' or 'effect of pollutants' alone(1)
Answer: (a) mining → raw materials; pressing cans → manufacturing and packaging; fridge → use and operation; landfill → disposal (b) e.g. energy used
Examiner tip: Do not write 'pollution' for (b): the harm caused by pollutants is exactly the part of an LCA that is hard to value.

3Grade 1–3Foundation4 marks

Glass is made by heating sand, sodium carbonate and limestone in a furnace. Sand and limestone are quarried from the ground.

(a) Give two ways that used glass bottles can be dealt with to reduce the use of raw materials. [2]

(b) Give one way that quarrying sand and limestone damages the environment. [1]

(a) (washed and) reused (as bottles again); allow refilled(1)
(a) crushed and melted (to make new glass / new bottles); allow recycled; 'recycled' and 'crushed and melted' count as one way only(1)
(b) any one from: destroys habitats / landscape; scars on the landscape / ugly; noise; dust; traffic (from lorries); uses (fossil) fuel / releases carbon dioxide; ignore 'pollution' unqualified(1)
(c) the bottle does not need to be heated / melted (in a furnace) – it only needs washing; allow it is not crushed and melted; ignore 'it is not recycled'(1)
Answer: (a) reuse (wash and refill); crush and melt to make new glass (b) e.g. destroys habitats (c) no melting needed, only washing
Examiner tip: In (a), 'recycle' and 'crush and melt' are the same method, so you need reuse as the second way.

4Grade 4–55 marks

A student compares the energy used over the life cycle of drinking water bottles.

Option 1: 100 single-use plastic bottles, each used once and then thrown away.
Option 2: one steel bottle, used 100 times and washed in hot water after each use.

The bar chart shows the student's results for each stage of the life cycle.

(a) Which stage uses the most energy for the 100 plastic bottles? [1]

(b) The use stage for the plastic bottles is zero, but it is 60 MJ for the steel bottle. Suggest why. [1]

(c) Calculate how much less energy is used by the steel bottle than by the 100 plastic bottles over the whole life cycle. [2]

(d) Steel is made from iron ore. Give one environmental impact of making the steel bottle that is not shown by the bar chart. [1]

(a) raw materials / extracting and processing raw materials(1)
(b) the steel bottle has to be washed (in hot water) after each use / heating water uses energy, but plastic bottles are thrown away (not washed); allow steel bottle is reused(1)
(c) totals: plastic = 180 + 120 + 0 + 40 = 340 (MJ) and steel = 40 + 30 + 60 + 10 = 140 (MJ); allow either total correct for this mark if the other is clearly from the chart ± 2(1)
(c) 200 (MJ); allow ecf: plastic total − steel total; correct answer with no working scores 2(1)
(d) any one from: mining (iron ore) damages the landscape / destroys habitats; produces waste rock / spoil heaps; uses a limited / finite resource (iron ore); releases carbon dioxide / pollutants (e.g. from the blast furnace); uses water; ignore 'uses energy' (shown by the chart)(1)
Answer: (a) raw materials (b) the steel bottle is washed in hot water after every use (c) 200 MJ (d) e.g. mining damages the landscape
Examiner tip: Add every bar for each option before subtracting; students often compare only one stage (e.g. 180 − 40).

5Grade 4–54 marks

A builder is choosing between wooden window frames and plastic (PVC) window frames. A report on the two types of frame uses life cycle assessments (LCAs).

(a) Give two things that can be given a numerical value easily in an LCA. [2]

(b) The report states: 'Wooden frames are better because the pollutants released when they are made are less harmful.'

Explain why this part of an LCA is not purely objective. [2]

(a) any two from: (use of) energy; (use of) water; (use of) resources / raw materials; (amount of) waste produced; allow mass of CO₂ released — first(1)
(a) second from the list; do not accept 'pollution' or 'harm to the environment'(1)
(b) it is difficult to give the effects of pollutants (a) numerical value(s) / to measure how harmful pollutants are(1)
(b) (so) it needs value judgements / opinions, which may differ between people (e.g. whether harm to wildlife matters more than harm to people / the author may be biased); allow the result depends on who carries out (or pays for) the LCA(1)
Answer: (a) e.g. energy used; water used (b) the effects of pollutants are hard to give values to, so value judgements (opinions) are needed
Examiner tip: Say why it is not objective: values for pollutant harm must be judged, not measured, so two people can reach different conclusions.

6Grade 6–76 marks

A company that sells reusable cloth nappies uses this headline in an advert:

'Switch to our nappies – over 75% less carbon dioxide!'

The table shows LCA data for the nappies used by one baby over 2.5 years.

Stage	Mass of CO₂ released by disposable nappies in kg	Mass of CO₂ released by reusable nappies in kg
Raw materials and manufacture	400	90
Use (washing and drying)	10	380
Disposal	140	20

(a) Show that the advert's figure is correct for the raw materials and manufacture stage only. [2]

(b) Calculate the percentage reduction in the total mass of CO₂ released when reusable nappies are used instead of disposable nappies. Give your answer to 2 significant figures. [2]

(a) (400 − 90) ÷ 400 (× 100) / 310 ÷ 400 (× 100)(1)
(a) = 77.5 (%) (which is over 75%); allow 78 (%) or 0.775 with a statement that it is greater than 75%(1)
(b) totals 550 (kg) and 490 (kg) and (550 − 490) ÷ 550 (× 100) / 60 ÷ 550 (× 100)(1)
(b) = 11 (%) to 2 s.f.; 10.9 or 10.909… (%) (not 2 s.f.) scores 1 mark only; correct answer with no working scores 2(1)
(c) the advert uses only (one stage /) the manufacture stage / it is a selective (or abbreviated) LCA / it leaves out the use stage(1)
(c) the reusable nappies release much more CO₂ in use (washing and drying: 380 kg compared with 10 kg), so over the whole life cycle the saving is only about 11% (not over 75%); allow ecf from (b)(1)
Answer: (a) 310 ÷ 400 × 100 = 77.5% (b) 11% (c) it quotes only the manufacture stage (a selective LCA); washing and drying the reusable nappies releases 380 kg, so the overall saving is only 11%
Examiner tip: For (c), name the missing stage and quote the data: 'it only uses part of the LCA' gets 1 mark, linking it to the 380 kg from washing gets the second.

7Grade 4–54 marks

Aluminium can be made from its ore or by recycling used aluminium.

Method	Energy needed to make 1 kg of aluminium in MJ
From aluminium ore	150
By recycling used aluminium	9

(a) Calculate the percentage of energy saved when 1 kg of aluminium is made by recycling instead of from its ore. [2]

(b) Give one reason, other than saving energy, why aluminium should be recycled. [1]

Suggest how the steel cans can be separated from the aluminium cans. [1]

(a) (150 − 9) ÷ 150 (× 100) / 141 ÷ 150 (× 100)(1)
(a) 94 (%); correct answer with no working scores 2; 6% (the percentage used, not saved) scores 1(1)
(b) any one from: aluminium ore / bauxite is a limited / finite resource; less mining / quarrying (so less damage to the environment / habitats); less waste in landfill; ignore 'cheaper' unqualified(1)
(c) use a magnet (steel is magnetic, aluminium is not); allow electromagnet(1)
Answer: (a) 94% (b) e.g. aluminium ore is a finite resource (c) use a magnet – steel is attracted, aluminium is not
Examiner tip: Read the question: it asks for the percentage saved, so subtract first; 9 ÷ 150 × 100 = 6% is the energy used.

8Grade 6–7Higher6 marks

Used glass can be crushed to make cullet. Cullet is added to the raw materials in a glass furnace.

Melting the raw materials to make 1 tonne of new glass with no cullet needs 6.0 GJ of energy.
For every 10% of cullet in the mixture, the energy needed falls by 2.5% of this value.

(a) Calculate the energy needed to make 1 tonne of glass when the mixture is 60% cullet. [2]

(b) A factory makes 400 tonnes of glass each day. Calculate the energy saved each day by using a mixture that is 60% cullet instead of using no cullet. [1]

(d) Clear glass bottles are made from cullet that contains only clear glass. Explain why the cullet must be separated by colour. [1]

(a) 6 × 2.5 = 15% reduction or 6.0 × 0.15 = 0.9 (GJ saved per tonne)(1)
(a) 5.1 (GJ); correct answer with no working scores 2(1)
(b) 360 (GJ); allow ecf: (6.0 − answer to (a)) × 400(1)
(c) any two from: less sand / limestone (raw material) quarried (so less damage to landscape / habitats); conserves limited raw materials; less glass waste in landfill; less fossil fuel burned (so less CO₂ released) — first; do not accept 'saves energy' (given in question)(1)
(c) second point from the list(1)
(d) coloured glass contains different substances / the colour stays when glass is melted, so mixed cullet would give glass with the wrong colour / properties; allow the new glass would not be clear(1)
Answer: (a) 5.1 GJ (b) 360 GJ (c) e.g. less quarrying of sand and limestone; less glass sent to landfill (d) the colour stays when glass is melted, so mixed cullet would give coloured glass
Examiner tip: In (a), 2.5% is per 10% of cullet: work out 6 × 2.5 = 15% before using it. Using 60 × 2.5 is a common slip.

9Grade 8–9Higher6 marks

A dairy is deciding whether to sell milk in reusable glass bottles or in single-use plastic (HDPE) bottles. Each glass bottle is collected, washed and refilled. Used plastic bottles are put out for recycling.

	Glass bottle	Plastic bottle
Raw materials	sand, limestone, sodium carbonate	crude oil
Mass of one empty bottle in g	280	40
Energy to make one bottle in MJ	7.5	2.4
Average number of times each bottle is filled	15	1
Energy to wash one bottle in MJ	0.25	0
Energy (fuel) to transport one bottle on one trip in MJ	0.40	0.10
End of life	crushed and melted to make new glass	60% recycled; the rest goes to landfill

Evaluate the use of reusable glass bottles compared with single-use plastic bottles for milk.

Use the information in the table and your own knowledge. [6]

glass: made from sand and limestone, which are abundant but are quarried (damages the landscape); plastic: made from crude oil, a finite / non-renewable resource(1)
energy to make one bottle: glass 7.5 MJ is about 3 times that for plastic 2.4 MJ(1)
but each glass bottle is used 15 times: making energy per fill = 7.5 ÷ 15 = 0.5 MJ(1)
energy per fill including washing and transport: glass 0.5 + 0.25 + 0.40 = 1.15 MJ; plastic 2.4 + 0.10 = 2.5 MJ, so plastic uses about twice as much energy per fill(1)
glass bottles are heavier (280 g vs 40 g), so need more fuel to transport (0.40 vs 0.10 MJ per trip) and release more CO₂ from transport(1)
glass is fully recycled at end of life (crushed and melted); 40% of plastic bottles go to landfill, where plastic is not biodegradable / persists for a long time / uses land(1)
reusing reduces the use of limited resources and the amount of waste more than recycling does(1)
limitations: the advantage of glass depends on bottles actually being returned – if each bottle were filled only 4 times, 7.5 ÷ 4 + 0.65 ≈ 2.5 MJ, about the same as plastic; the table only compares energy, and the effects of pollutants (e.g. from quarrying or landfill) need value judgements(1)
judgement, e.g. glass bottles are better overall because they use less than half the energy per fill and produce less waste, provided they are returned and reused many times(1)

Level	Marks	What it looks like
Level 3	5–6	A balanced evaluation using data from the table for both bottles, with calculations or comparisons (e.g. energy per trip) and links to resources, energy or waste. A conclusion is given that is supported by the evidence and recognises at least one limitation or condition.
Level 2	3–4	Advantages and disadvantages of both bottles are described, with some use of the data. A conclusion may be given but it is only partly supported, or the comparison is mostly one-sided.
Level 1	1–2	Simple statements about one or both bottles, e.g. 'glass can be reused' or 'plastic is made from crude oil', with little or no use of the data and no clear judgement.
No relevant content	0	No relevant content.

Answer: Glass: about 1.15 MJ per fill vs 2.5 MJ for plastic, less landfill waste and no crude oil, but heavier to transport and only better if bottles are returned enough times; a supported judgement (usually glass) is required for Level 3.
Examiner tip: To reach Level 3 you must turn the raw data into a fair comparison per fill: 7.5 MJ ÷ 15 trips, then add washing and transport.

10Grade 8–9Higher6 marks

The table shows LCA data for the mass of carbon dioxide released by a petrol car and by an electric car.

Stage	Petrol car	Electric car
Raw materials and manufacture (including battery) in tonnes	6.0	10.5
Use, in g per km driven	180	60
Disposal in tonnes	0.4	0.7

1 tonne = 1 000 000 g

(a) Calculate the distance the cars must be driven before the total mass of CO₂ released by the electric car becomes less than that released by the petrol car. Include disposal for both cars. [3]

(b) Each car is driven 150 000 km in its lifetime. Calculate the percentage by which the total mass of CO₂ released by the electric car is lower than that released by the petrol car. [2]

(c) The figure of 60 g per km for the electric car was calculated for one country. Suggest why the figure would be different in another country. [1]

(a) difference in manufacture + disposal = (10.5 + 0.7) − (6.0 + 0.4) = 4.8 (tonnes) or equation 6.4 + 0.00018d = 11.2 + 0.00006d (in tonnes) or equivalent in g(1)
(a) CO₂ saved per km = 180 − 60 = 120 (g) and 4.8 tonnes = 4 800 000 g(1)
(a) 4 800 000 ÷ 120 = 40 000 (km); correct answer with no working scores 3(1)
(b) totals: petrol 6.4 + 27 = 33.4 (tonnes) and electric 11.2 + 9 = 20.2 (tonnes)(1)
(b) (33.4 − 20.2) ÷ 33.4 × 100 = 40 (%); allow 39.5 (%); allow ecf from incorrect totals(1)
(c) electricity is generated in different ways in different countries / the proportion of electricity from fossil fuels (e.g. coal) or from renewables / nuclear differs, so a different mass of CO₂ is released per unit of electricity; ignore 'different cars / roads'(1)
Answer: (a) 40 000 km (b) 40% (39.5%) (c) different mix of fossil fuel and renewable electricity generation
Examiner tip: Convert tonnes to grams (× 1 000 000) before dividing by g per km; mixing units gives 0.04 km or 40 000 000 km.

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