78% nitrogen; 21% oxygen; 1% argon and other gases.
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How do we find out the % of oxygen in the air?
Passing air over heated copper.
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Which gases formed the Earth's atmosphere? How were they produced?
Carbon dioxide, water vapour, lava and dust; from volcanoes.
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How did oceans form?
When the earth cooled down, condensed water then formed oceans.
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What did simple bacteria do that allowed organisms to evolve?
Photosynthesis; they removed carbon dioxide from the air and produced oxygen.
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How were fossil fuels formed?
Carbon dioxide removed by plants and animals dying, and becoming buried. The buried material became fossil fuels millions of years later.
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How were sedimentary rocks formed?
Carbon dioxide dissolved in oceans reacts with salts to form insoluble calcium carbonate, which forms sediments, which are buried to form sedimentary rocks.
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How have ideas of the composition of the atmosphere changed over time?
60 years ago, people believed that the early atmosphere was mainly made up of ammonia and methane. Recent discoveries suggest that it was largely carbon dioxide.
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Give 3 examples of pollutants that are harmful to our health.
Hydrocarbon fuel + oxygen -> carbon dioxide + water + energy
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What is oxidation?
When oxygen is added to a substance.
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What is reduction?
When a reactant loses oxygen.
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What is combustion? Is it an oxidation or reduction reaction? Why?
Burning; an oxidation reaction, because oxygen is needed to burn any fuel.
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What are molecules?
Atoms of non-metal elements joined together.
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Explain the Law of Conservation of Mass.
In a chemical reaction, mass is not lost; it is transferred between reactants and products.
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Sulphur + Oxygen ->
Sulphur dioxide
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Which two businesses cause the most pollution?
Transport and power stations.
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What oxide do car engines make? What is the outcome of this?
Nitrogen dioxide, which damages buildings and contributes to acid rain.
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Carbon atom colours? (Yellow/Red/Black/White/Blue)
Yellow = Sulphur | Oxygen = red | Carbon = Black | White = Hydrogen | Blue = Nitrogen
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How are pollutants removed from the air?
When particulates settle on surfaces; when sulphur and nitrogen ocides react with oxygen and water; in photosynthesis; when it dissolves in oceans or rain water.
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How can we improve power stations?
Removing electricity; turning things off; burning less; removing sulphur from oil/gas before burning it; flue gas desulfurisation.
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What is FGD?
Flue gas desulfurisation is a set of technologies used to remove sulphur dioxide from fossil-fuel power plants.
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List two wet scrubbing methods, and explain why they are used.
Using an alkaline slurry of lime and water to make calcium sulphate, OR using sea water to absorb the sulphur dioxide. They are used to remove sulphur dioxide from power stations.
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How do we reduce air pollution?
Use less cars; use cleaner fuels; use more public transport; remove pollutants from exhausts.
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