The four stages of a life cycle assessment, why parts of it involve judgement rather than measurement, and the case for reducing, reusing and recycling. Chemistry only content.
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1.What is a life cycle assessment?
An assessment of the environmental impact of a product across every stage of its life.
2.State the four stages considered in a life cycle assessment.
Extracting and processing raw materials, manufacturing and packaging, use and operation during its lifetime, and disposal at the end of its life.
3.What is also included alongside those four stages?
Transport and distribution at every stage.
4.Which parts of a life cycle assessment can be measured accurately?
The use of water, resources, energy sources and the production of some wastes.
5.Which parts involve judgement rather than measurement?
Allocating numerical values to pollutant effects, which means the assessment is not purely objective.
6.Why does that matter?
Because judgements can be influenced by the people carrying out the assessment, life cycle assessments can be biased or used selectively for advertising.
7.Why is a selective life cycle assessment misleading?
It may present only the favourable stages, giving a false impression of how environmentally friendly a product is.
8.Compare a plastic bag and a paper bag at the raw material stage.
The plastic bag comes from crude oil, a finite resource. The paper bag comes from timber, which is renewable but requires land and water.
9.Compare them at the disposal stage.
Paper is biodegradable and easily recycled. Plastic is not biodegradable and persists in the environment for a very long time.
10.State the three Rs in order of preference.
Reduce, reuse, recycle.
11.Why is reducing better than recycling?
Using less in the first place avoids the energy and resources needed to make, transport and later process the product at all.
12.Give an example of reusing.
Refilling glass bottles, or using a shopping bag many times.
13.How are metals recycled?
They are melted down and cast into the shape of the new product. Some may need to be separated by type first.
14.Why is recycling metal worthwhile?
It uses far less energy than extracting the metal from its ore, and it conserves a finite resource.
15.Why is recycling aluminium particularly worthwhile?
Extracting it requires electrolysis, which uses enormous amounts of electricity. Melting recycled aluminium uses a small fraction of that.
16.How is glass recycled?
Bottles can be reused, or crushed and melted to make different glass products.
17.Why does recycling reduce environmental damage?
Less quarrying and mining is needed, less waste goes to landfill, and less energy is used overall.
18.Why can some products not be recycled easily?
They are made of several materials bonded together, which are difficult and expensive to separate.
19.What does biodegradable mean?
It can be broken down by microorganisms in the environment.
20.Why is a life cycle assessment useful to a company?
It shows which stage causes the most environmental harm, so effort can be directed where it makes the biggest difference.
21.Why must transport be included?
Moving raw materials and finished goods uses fuel and produces emissions, sometimes more than manufacturing itself.
22.Why is disposal an important stage to assess?
A product that lasts a long time in use may still cause serious harm if it cannot be recycled or breaks down slowly.
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