What evidence can geologists use to explain the history of Earth's surface?
mountain building, erosion, sedimenatation, dissolving and evaporation
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What do geologists use to track the movements of tectonic plates?
magnetic clues in rocks
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Why did different rocks in Britain form in different climates?
because of the movements of the continents
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What pieces of evidence do geologists look for in sedimentary rocks?
fossils, shapes of water borne grains compared to air blown grains, presence of shell fragments and ripples from sea or river bottom
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What is salt important for?
too food industry, as a source of chemicals and to treat roads in winter
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Where can salt be obtained from?
from the sea or underground
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How can salt be obtained?
mining the solid (rock salt) or pumping water into the salt deposit and extracting the solution of salt (brine)
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What is the significance of obtaining salt using different methods?
if salt is mined as a solid it is more useful for roads but if it is extracted from solution it is better for the food industry because it is purified
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What environmental impacts can extracting salt have?
dissolving underground salt can lead to the ground subsiding and buildings collapsing. Salt waste can also dry up animals and plants
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What are the advantages of adding salt to food?
it can be used as a preservative and for flavour
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What are the health implications of eating too much salt?
it can lead to high blood pressure and further circulatory conditions
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How does the government have a role in the food industry?
they carry out risk assessments in relation to chemicals in food and advise the public on the effect food has on our health
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What are alkalis needed for?
to neutralise acid soils, make chemicals that bind natural dyes to cloth, convert fats and oils into soap and to manufacture glass
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What are traditional sources of alkali?
burnt wood or stale urine
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What are soluble hydroxides and carbonates?
alkalis
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What lead to a shortage of alkali in the nineteenth century?
increased industrialisation
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Why did the first process fro manufacturing alkalis cause a lot of pollution?
alkali was made from salt and limestone, using coal as a fuel and it released large volumes of an acid gas and created great heaps of waste that released a toxic gas
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How can pollution problems be sometimes solved?
by turning waste into useful products
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What domestic purposes does chlorine have?
chlorine can kill microorganisms in domestic water supplies and can be used as a bleach
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What are disadvantages to chlorinating drinking water?
chlorine might react with organic chemicals in the water and produce other harmful chemicals
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When does electrolysis occur?
when an electric current is used to split up a liquid or dissolved compound (called the electrolyte)
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How is chlorine now obtained?
through the electrolysis of brine
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What products from brine are useful chemicals?
sodium hydroxide, hydrogen and chlorine
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Why do some toxic chemicals cause problems?
they persist in the environment, can be carried over long distances and may accumulate in food and human tissues
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What is PVC?
a polymer that contains chlorine as well as carbon and hydrogen
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Why can plasticizers have harmful effects?
the plasticizer can leak out from the plastic and into the surroundings, where they can have harmful effects
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What does the Life Cycle Assessment have to consider when looking at a product?
the use of resources, the energy input or output and the environmental impact
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Other cards in this set
Card 2
Front
What do geologists use to track the movements of tectonic plates?
Back
magnetic clues in rocks
Card 3
Front
Why did different rocks in Britain form in different climates?
Back
Card 4
Front
What pieces of evidence do geologists look for in sedimentary rocks?
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