Using resources — GCSE Chemistry Revision
Everything you need to revise using resources for GCSE Chemistry: clear notes, the key facts and terms to learn, the mistakes that cost students marks, and practice questions with answers.
Revision notes
Finite and Renewable Resources
Resources are materials found on Earth that humans use. They can be classified as finite (non-renewable) or renewable. Finite resources, such as fossil fuels (coal, oil, gas) and metal ores, are used faster than they can be formed and will eventually run out. Renewable resources, like timber and fresh water, can be replenished naturally within a human lifetime. Sustainable development aims to meet the needs of the present without compromising the ability of future generations to meet their own needs, often by using renewable resources more efficiently.
The Earth's Resources and Extraction
The Earth's crust provides most of the resources we need, including metals and crude oil. Obtaining these resources often involves mining, drilling, or quarrying. For instance, metal ores are rocks containing enough metal compounds to make extraction economical. Many useful materials, like plastics, are synthetic and made from finite resources such as crude oil. Extracting and processing these materials can have significant environmental impacts, including habitat destruction, pollution, and high energy consumption, contributing to global warming.
Recycling and Life Cycle Assessment (LCA)
Recycling involves processing waste materials into new products to prevent waste of potentially useful materials, reduce consumption of fresh raw materials, reduce energy usage, reduce air and water pollution, and lower greenhouse gas emissions. A Life Cycle Assessment (LCA) is a 'cradle-to-grave' analysis of the environmental impact of a product. It considers raw material extraction, manufacturing, distribution, use, and disposal. LCAs help identify stages where environmental impact is highest and inform decisions about product design and material choices.
Water Treatment for Potable Water
Potable water is water safe for human consumption. It is not pure H₂O, but contains dissolved substances beneficial for health. In the UK, the main sources of potable water are fresh water from lakes, rivers, and reservoirs. The treatment process typically involves screening (removing large solids), sedimentation (allowing smaller suspended solids to settle), and filtration (passing water through sand beds to remove fine particles). Finally, sterilisation (e.g., using chlorine or UV light) kills harmful microorganisms, making the water safe to drink.
Key facts
- Finite resources are used faster than they form.|Renewable resources can be replenished naturally.|Life Cycle Assessments (LCAs) evaluate environmental impact.|Potable water is safe to drink, not chemically pure.|Recycling reduces waste and saves resources.|Synthetic materials are often made from crude oil.
Key terms
- Finite resource::A natural resource that cannot be readily replaced by natural means at a quick enough pace to keep up with consumption.|Renewable resource::A natural resource that can be replenished naturally and sustainably.|Sustainable development::Meeting the needs of the present without compromising the ability of future generations to meet their own needs.|Potable water::Water that is safe to drink, containing beneficial dissolved substances, but not chemically pure.|Life Cycle Assessment (LCA)::An evaluation of the environmental impacts of a product, process, or service throughout its entire life cycle.|Recycling::Processing used materials into new products to prevent waste and reduce the consumption of fresh raw materials.
Common mistakes
- Confusing potable water with pure water (potable is safe to drink, pure is just H₂O).|Assuming all synthetic materials are environmentally damaging without considering their full life cycle.|Forgetting that even renewable resources like timber need careful management to be truly sustainable.|Only considering the 'disposal' stage when thinking about environmental impact, ignoring extraction and manufacturing.
Exam tips
- When asked about environmental impacts, always consider different stages of a product's life cycle.|For water treatment, remember the three key stages: screening/sedimentation, filtration, and sterilisation.|Be able to give examples of both finite (e.g., crude oil, metal ores) and renewable (e.g., timber, solar energy) resources.|Understand that LCAs are complex and can be biased, and be prepared to explain why (e.g., selective data).
Quick quiz
1. Which of the following is a finite resource?
- Solar energy
- Timber
- Crude oil
- Freshwater
Show answer
Crude oil — Crude oil is a fossil fuel, which forms over millions of years and is used much faster than it can be replenished, making it a finite (non-renewable) resource. Solar energy, timber, and freshwater are generally considered renewable.
2. What is the primary purpose of sterilisation in water treatment?
- To remove large insoluble particles.
- To remove dissolved salts.
- To kill harmful microorganisms.
- To improve the taste of the water.
Show answer
To kill harmful microorganisms. — Sterilisation, typically using chlorine or UV light, is the final stage of water treatment designed to kill pathogenic (harmful) bacteria and other microorganisms, making the water safe to drink. Filtration removes small particles, and desalination removes dissolved salts.
3. A Life Cycle Assessment (LCA) considers a product's environmental impact from:
- Manufacturing to disposal.
- Raw material extraction to manufacturing.
- Raw material extraction to disposal.
- Use to disposal.
Show answer
Raw material extraction to disposal. — An LCA is a 'cradle-to-grave' analysis, meaning it covers the entire life cycle of a product, from the extraction of raw materials, through manufacturing, use, and finally to its disposal.
4. Which statement best describes potable water?
- It is chemically pure H₂O.
- It contains no dissolved substances.
- It is safe to drink.
- It is only found in natural springs.
Show answer
It is safe to drink. — Potable water is water that is safe for human consumption. It is not chemically pure H₂O, as it contains beneficial dissolved minerals. It can come from various sources and undergoes treatment.
5. What is a major environmental benefit of recycling aluminium cans?
- It increases the amount of land needed for landfills.
- It requires more energy than extracting new aluminium.
- It conserves bauxite ore, a finite resource.
- It creates more air pollution during processing.
Show answer
It conserves bauxite ore, a finite resource. — Recycling aluminium significantly reduces the need to mine new bauxite ore, which is a finite resource. It also saves a substantial amount of energy compared to primary production and reduces landfill waste and pollution.
Exam-style questions
Explain two ways in which recycling materials benefits the environment. [2 marks]
Show mark scheme
- Reduces the amount of waste sent to landfill (or incineration).
- Reduces the demand for new raw materials/finite resources (e.g., metal ores, crude oil).
- Saves energy required to extract/process new raw materials.
- Reduces pollution associated with extraction/manufacturing of new materials.
Describe the three main stages involved in treating fresh water to make it potable. [3 marks]
Show mark scheme
- Screening and/or sedimentation (to remove large insoluble particles / allow suspended solids to settle).
- Filtration (to remove fine suspended particles by passing through sand/gravel beds).
- Sterilisation (to kill harmful microorganisms/bacteria, e.g., using chlorine/UV light).
Analyse why a Life Cycle Assessment (LCA) can be complex and sometimes biased. [3 marks]
Show mark scheme
- LCAs are complex because they involve collecting vast amounts of data from all stages of a product's life.
- It can be difficult to quantify all environmental impacts (e.g., aesthetic pollution, social impacts).
- LCAs can be biased if the company carrying out the assessment selects data to present a favourable outcome.
- It can be hard to compare different types of environmental impacts (e.g., CO2 emissions vs. water pollution).
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