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28 Cards in this Set
- Front
- Back
What is the atmosphere composed of?
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Nitrogen Oxygen Argon Small amounts of water vapour, carbon dioxide and other gases |
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What are the relative proportions of the main gases in the air?
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78% nitrogen 21% oxygen 1% argon, carbon dioxide, water vapour |
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What can affect air quality?
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Human activity or natural processes (volcanoes) may release other gases or particulates into the atmosphere.
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How long ago was the Earth formed?
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4.5 billion years ago
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What did water vapour condense to form when the Earth cooled?
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The oceans
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How did the evolution of photosynthesising organisms add oxygen to and remove carbon dioxide from the atmosphere?
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Cyanobacteria (early form of simple plant) were able to photosynthesise so took in carbon dioxide and released oxygen into the atmosphere.
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How was carbon dioxide removed from the atmosphere other than through photosynthesising organisms?
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It dissolved into the oceans and formed sedimentary rocks and also by the formation of fossils.
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How has human activity changed the composition of the atmosphere?
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By adding small amounts of carbon monoxide, nitrogen oxides and sulphur dioxide and adding extra carbon monoxide and small particulates to the atmosphere.
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What are the problems of pollutants being added to the atmosphere?
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Some are directly harmful to humans (e.g carbon monoxide reduces oxygen carrying capacity of blood) Some harmful to the environment (sulphur dioxide and nitrogen dioxide causes acid rain) |
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What is coal mainly made up of?
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Carbon
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What are petrol, diesel fuel and fuel oil mainly compounds of?
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Hydrogen and carbon (hydrocarbons)
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When fuel burns, what happens to the atoms of carbon/hydrogen from it?
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They combine with atoms of oxygen in the air to produce carbon dioxide and/or water.
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What is oxidation?
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The gain of oxygen by a substance, substance chemically combining with oxygen. |
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What is reduction?
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The loss of oxygen by a substance
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When does fuel burn more rapidly?
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In pure oxygen rather than in air.
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What happens to the atoms during a chemical reaction?
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They are rearranged
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What is meant by conserving mass?
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During the course of a chemical reaction, the number of atoms of each element must be the same in the products as in the reactants.
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How is sulphur dioxide produced if the fuel that is burned contains any sulphur?
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Burning a substance requires oxygen so when fuel containing sulphur is burnt, the sulphur combines with the oxygen to form sulphur dioxide.
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What does burning fossil fuels in power station and for transport pollute the atmosphere with?
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Carbon dioxide and sulphur. Carbon monoxide and particulate carbon (from incomplete combustion). Nitrogen oxides (from reaction between atmospheric nitrogen and oxygen at high temperatures inside engines. |
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When is nitrogen oxide formed and what does it oxidise to?
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Formed during the combustion of fuels in the air and oxidises to nitrogen dioxide.
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Atmospheric pollutants cannot just disappear. Give examples of where they go.
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Particulate carbon- deposited on surfaces Sulphur dioxide/nitrogen dioxide- react with oxygen to produce acid rain Carbon dioxide- used by plants in photosynthesis and dissolves in rain and sea water |
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How can atmospheric pollution caused by power stations that burn fossil fuels be reduced?
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Using less electricity. Removing sulfur from natural gas or fuel oil.Removing sulfur dioxide and particulates from the flue (pipe) gases emitted by coal-burning power stations. |
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How is sulphur dioxide removed from flue gases by wet scrubbing (control devices for removing particles and/or gases from industrial exhaust streams)?
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Using an alkaline slurry e.g. a spray of calcium oxide and water. Using sea water |
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What is the only way to produce less carbon dioxide?
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Burn less fossil fuels
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How can atmospheric pollution caused by motor vehicle exhaust emissions be reduced?
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Efficient engines (burn less) Low sulphur fuels Catalytic converters Balance private and public transport use Legal limits to exhaust emissions (MOT tests) |
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What does a catalytic converter do?
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Reduce production toxic gases Use platinum and rhodium catalyst with high SA - increases rate reaction of carbon monoxide and unburnt fuel from exhaust gases with oxygen from the air. Product - carbon dioxide and water- less harmful to the environment. |
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What are the benefits and problems of using biofuel as an alternative to fossil fuels for motor vehicles?
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Benefits: renewable, made from plants that absorb CO2 as they grow Problems: still releases CO2 when burnt, more land needed to grow sufficient amounts of plants to use for fuel |
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What are the benefits and problems of using electricity as an alternative to fossil fuels for motor vehicles?
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Benefits: does not produce waste gases when used Problems: often comes from power stations that burn fossil fuels, short range before needing to be recharged, recharging takes a long time |