9 E
Summary Sheets
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9 E
Summary Sheets
Problems with making and using materials
Burning fossil fuels provides the energy needed to make materials but is also linked to:
● acid rain from production of sulfur dioxide
● increase in carbon dioxide levels and the greenhouse effect
● soot dirtying buildings and damaging health.
Toxic substances released in waste get into food chains.
As large animals eat lots of smaller animals, toxin levels increase (biomagnification) and can reach
harmful levels in humans.
Non-biodegradable polymer waste causes pollution problems and dangers to animals for years.
Solutions to these problems include …
● removal of sulfur from fuels
● reduction in the use of fossil fuels and use of more renewable energy sources
● control of hazardous waste from factories
● use of biodegradable polymers, which break down in the soil, so they disappear more quickly.
Recycling materials to use again …
● reduces our use of landfill sites
● reduces the need to burn fossil fuels
● reduces pollution from manufacturing process
● saves our resources of raw materials, e.g. metal ores
for metals and wood for paper.
Examples of materials that can be recycled
Metals – by separating and melting.
Glass – by separating colours and melting.
Polymers – by using recycle labels.
Paper – by removing ink and adding water to make a pulp. Recycling saves the Earth’s resources.
Concrete – by crushing and grading.
Endothermic and exothermic reactions
Exothermic reactions transfer energy into the surroundings and so increase the temperature
around them, e.g. combustion reactions. Endothermic reactions transfer energy from the
surroundings and so decrease the temperature around them, e.g. decomposition reactions.
Peer review: how scientific discoveries are checked
Scientists carry out investigations and write a scientific paper on their findings. They send their
paper to a scientific journal. An editor reads the paper. If it is interesting the editor sends it to
scientists who work in same area for peer review. The scientists check that the paper has valid
conclusions, that it is original and that the experiments work.
Depending on the review, the paper is recommended for publication, amendment or rejection.
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