Materials and their life cycle
A plastic is a polymer: thousands of identical small molecules hooked into one very long chain, and that length is what gives it its properties, not what it is made of — the same piece repeated differently gives anything from a shopping bag to body armour. A battery is a redox reaction forced to happen in two separate places, so that the electrons have to take the long way round outside: it does not store electricity, it stores an unfinished reaction. And any product's environmental cost has to be added up across the whole thing, from extraction to landfill, not just the last step: a cloth bag beats a plastic one only if it is used a great many times, because making it costs considerably more. Recycling aluminium is the clearest case: getting it out of the ore means prising it off the oxygen by electrolysis and that eats an enormous amount of electricity, while melting a used can costs around five per cent of that energy.
Where this sits
- Comes after
- Air, water and soil
Exercises from this rung
Generated by the app, from easiest to hardest
What is a plastic, chemically?
- Very long chains of the same piece repeated
- Something derived from glass, but soft
- A metal treated with heat and oil
- A mixture of ground-up minerals
Why A polymer: thousands of identical small molecules hooked into one very long chain. That length is what gives it its properties, not what it is made of: the same piece repeated differently gives anything from a shopping bag to body armour. And nearly all those pieces come from oil today.
easierWhat is inside a battery?
- A redox reaction split into two halves
- A gas under pressure that pushes
- Electricity stored in a reservoir
- A magnet and a coil that spin
Why An oxidation-reduction reaction forced to happen in two separate places: the electrons that would pass straight from one reactant to the other have to take the long way round outside, and that detour is the current. A battery does not store electricity: it stores an unfinished reaction and runs it slowly.
in betweenPut a product's life cycle in order.
Answer The raw material is extracted, The product is manufactured, It is used for a while, It is recycled or ends up in landfill
Why And the environmental cost has to be added up across the whole thing, not just the last step. A cloth bag beats a plastic one only if it is used a great many times, because making it costs considerably more; counting only the end of the cycle leads to decisions that look good and are not.
harder