AQA GCSE Combined Science (8464), Higher tier · Chemistry › Using resources › Life cycle assessment and recycling
Practise Ways of reducing the use of resources. 12 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
Why reducing use, reusing and recycling materials saves limited resources and energy, how glass and metals are reused and recycled, and how to evaluate ways of reducing the use of resources from given information. Expect short explanations and data-based 'evaluate' questions on Paper 2.
Grade by grade
What you need to be able to do, from the first marks up to the top grade.
3
State the three ways to reduce resource useReduce use, reuse and recycle.
4
Name materials made from limited raw materialsMetals, glass, building materials, clay ceramics and most plastics.
5
Describe how glass and metals are recycledGlass is crushed and melted to make different glass products; metals are melted and recast or reformed.
5
Explain why recycling saves resources and energyLess of a limited raw material is used, and usually less energy than extracting and processing new material.
6
Explain why separation is needed for recyclingThe amount of separation depends on the material and the properties required of the final product.
7
Evaluate a recycling scheme from given dataBalance the resources and energy saved against the energy and cost of collecting, transporting and sorting.
Notes
Why reduce, reuse and recycle
Reducing use, reusing and recycling materials reduces the use of limited resources, the use of energy sources, waste and environmental impacts.
Metals, glass, building materials, clay ceramics and most plastics are made from limited raw materials.
Much of the energy used to make them comes from limited resources, such as fossil fuels.
Obtaining raw materials by quarrying and mining causes environmental impacts: scarred landscapes, lost habitats, noise, dust and heavy traffic.
Reuse and recycling
Reuse: some products, such as glass bottles, can be used again after washing.
Recycle: products that cannot be reused are recycled for a different use. Glass bottles can be crushed and melted to make different glass products.
Metals can be recycled by melting and recasting or reforming them into different products.
The amount of separation needed depends on the material and the properties required of the final product.
Example: some scrap steel can be added to iron from a blast furnace. This reduces the amount of iron that has to be extracted from iron ore.
Evaluating recycling
Advantages: saves limited raw materials (e.g. metal ores, sand, crude oil); usually uses less energy than extracting and processing new material; less mining and quarrying; less waste sent to landfill.
Disadvantages: collecting, transporting and sorting use energy and cost money; some materials are hard to separate; recycled material may be lower quality.
Metals that need a lot of energy to extract, such as aluminium (extracted by electrolysis), save the most energy when recycled.
Reducing use and reusing usually save more than recycling, because recycling still needs energy for melting and reprocessing.
Cheatsheet
Reduce, reuse, recycle → less use of limited resources and energy, less waste, smaller environmental impact
Limited raw materials: metals, glass, building materials, clay ceramics, most plastics
Glass bottles: reuse (wash and refill) or recycle (crush and melt → different glass products)
Metals: recycled by melting and recasting or reforming
Scrap steel added to blast furnace iron → less iron extracted from ore
Separation needed depends on the material and the properties of the final product
Percentage saved = (energy for new − energy for recycled) ÷ energy for new × 100
How to answer each type of question
Explain the advantages of recycling a material
2 to 4 marks5
Name the limited resource saved (e.g. iron ore, sand, crude oil).
Say that less energy is usually needed, so less fuel is burned.
Add a further consequence: less mining or quarrying, less waste in landfill.
For 'explain two', give each advantage and then its consequence.
Example. Explain two advantages of recycling steel cans instead of making new steel from iron ore. (4 marks)
Show the model answer
Less iron ore needs to be mined (1), so this limited resource lasts longer / there is less damage to the landscape (1). Less energy is needed than for extracting iron from its ore (1), so less fossil fuel is burned and less carbon dioxide is released (1).
Calculate the energy saved by recycling
2 to 3 marks6
Find the energy saved: energy for new material − energy for recycled material.
Divide by the energy for NEW material and multiply by 100.
Round as the question asks and include the % sign.
Example. Producing 1 tonne of aluminium from its ore uses 190 GJ of energy. Producing 1 tonne of aluminium from recycled cans uses 10 GJ. (a) Calculate the percentage of energy saved by recycling. Give your answer to 2 significant figures. (3 marks) (b) Suggest one reason why not all aluminium is recycled. (1 mark)
Show the model answer
(a) Energy saved = 190 − 10 = 180 GJ (1); 180 ÷ 190 × 100 = 94.7 (1); = 95% to 2 significant figures (1) (b) Any one: collecting and sorting the cans costs money and uses energy / not everyone puts cans out for recycling / some aluminium is joined to other materials that are hard to separate (1)
Evaluate ways of reducing the use of resources
4 to 6 marks7
Use the information: pick out energy, mass or cost figures and compare them.
Give points for and against each option.
Remember the hidden costs: collection, transport, washing and sorting.
Finish with a justified conclusion.
Example. A drinks company is deciding what to do with used glass bottles. Option A: collect, wash and refill the bottles. Energy used = 1.1 MJ per bottle. Option B: collect, crush and melt the bottles to make new bottles. Energy used = 2.8 MJ per bottle. Option C: make new bottles from sand, limestone and sodium carbonate. Energy used = 4.5 MJ per bottle. Evaluate the three options. (4 marks)
Show the model answer
Any four from: option A uses the least energy (1.1 MJ), less than half of B and about a quarter of C (1); A and B both save raw materials such as sand and limestone, so less quarrying is needed (1); bottles must be collected and transported back, and washing in A uses water and energy (1); chipped or broken bottles cannot be refilled, so some must still be recycled (1); C uses the most energy and uses up limited raw materials (1); conclusion: A is best for undamaged bottles, with B for damaged ones (1).
Shortcuts and memory tricks
Order of preference: reduce > reuse > recycle > landfill. Each step down uses more energy or wastes more.
Reuse = same job again (refill the bottle); recycle = new product (melt the bottle down).
Percentage saved: saving ÷ ORIGINAL × 100.
Mining and quarrying impacts: think 'scars, dust, noise, lorries'.
Where marks are lost
Mixing up reusing and recycling. Refilling a bottle is reuse; melting it down is recycling.
Saying recycling uses no energy. Collecting, transporting, sorting and melting all need energy.
Writing 'it's better for the environment' with no reason. Say what is saved: a named limited resource, energy or landfill space.
In percentage questions, dividing by the recycled value instead of the original value.
Exam technique
'Evaluate' needs points for and against, figures from the question, and a conclusion.
Name the specific limited resource (e.g. iron ore, sand, crude oil) rather than just 'resources'.
Look for the hidden costs in data questions: transport, sorting and separation.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Put these in order of preference for sustainability, most preferred first: recycle, reduce, reuse.
reduce, reuse, recycle
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
(a) Which is an example of reusing a product? Tick (✓) one box.[1]
Washing and refilling glass milk bottles
Melting scrap steel to make new steel
Crushing glass bottles to make new glass
Burning plastic waste to generate electricity
(b) Give two benefits of reducing the use of, reusing and recycling materials.[2]
(c) Glass bottles that cannot be reused are crushed and melted to make new glass products. Give one advantage of this compared with making glass from raw materials.[1]
Show the answer and mark scheme
(a)Answer: Washing and refilling glass milk bottles
(b)
reduces the use of limited resources
reduces the use of energy sources
reduces waste / landfill
reduces environmental impacts (e.g. of quarrying and mining)
(c)
less energy is needed / fewer raw materials (sand, limestone, sodium carbonate) are used / less quarrying
Question 2Medium5 marks
Metals are produced from limited raw materials.
(a) Describe how metals are recycled.[1]
(b) Some scrap steel is added to the iron produced in a blast furnace. Give one advantage of doing this.[1]
(c) Scrap aluminium used to make new drinks cans must be separated from other metals. Explain why.[2]
(d) Give one environmental impact of obtaining raw materials by mining and quarrying.[1]
Show the answer and mark scheme
(a)
they are melted and recast / reformed into different products
(b)
it reduces the amount of iron that needs to be extracted from iron ore
(c)
other metals would change the composition of the aluminium (alloy)
so the new metal would not have the properties needed for drinks cans
(d)
destroys habitats / scars the landscape / noise / dust / large amounts of waste rock / uses energy
Question 3Hard6 marks
Mixed plastic waste contains several different polymers. To make new food bottles, PET must be separated from the other plastics and cleaned very thoroughly. PET that is less well separated can be used to make fibres for fleece clothing.
(a) Explain why the amount of separation needed depends on the product being made.[2]
(b) Suggest two reasons why not all plastic waste is recycled.[2]
(c) A company claims its bottles are 'better for the environment' because they are made from 50% recycled PET. Evaluate this claim.[2]
Show the answer and mark scheme
(a)
food bottles need very pure PET to be safe and to have the required properties (e.g. strength, clarity)
fibres can still have suitable properties with small amounts of other polymers / less purity
(b)
collecting and sorting is expensive
different polymers are difficult to separate
some polymers (thermosetting polymers) cannot be melted and reshaped
waste is contaminated (e.g. with food)
recycled plastic may cost more than new plastic
(c)
using recycled PET reduces the use of crude oil (a finite resource), energy and waste
but half the PET is still new and the bottles are still single-use; the claim may be based on a selective LCA that ignores other stages (e.g. transport, disposal)