C6.3 Flashcards

1
Q

What was the composition of the atmosphere originally like, and why?

A
  • There was a lot of volcanic activity
  • They released a lot of water vapour and carbon dioxide
  • There were small amounts of other gases like ammonia and methane, but little to no oxygen
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2
Q

How did the atmosphere become mainly composed of carbon dioxide?

A
  • The water vapour condensed to form oceans
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3
Q

How did the atmosphere become full of oxygen?

A
  • Plants and algae photosynthesised, which reduced the amount of carbon dioxide and increased oxygen
  • At first this oxygen oxidised metals
  • As most of the metals became oxidised, free oxygen accumulated in the atmosphere
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4
Q

What is the atmosphere’s composition like today?

A
  • 78% nitrogen
  • 21% oxygen
  • Other gases such as water vapour, carbon dioxide and argon
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5
Q

What is the greenhouse effect?

A
  • Electromagnetic radiation at most wavelengths passes through the Earth’s atmosphere
  • The Earth absorbs most of the radiation and warms up
  • It then radiates the energy as infrared radiation
  • Some of the (longer wavelength) radiation goes into space
  • Some is absorbed by greenhouse gases in the atmosphere
  • They emit infrared radiation in all directions, which warms up the Earth’s atmosphere and surface
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6
Q

Give 2 examples of greenhouse gases.

A
  • Carbon dioxide
  • Methane
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7
Q

Why is the concentration of carbon dioxide in the atmosphere increasing?

A
  • The combustion of fossil fuels
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8
Q

What is the definition of anthropogenic?

A
  • Caused by human activity
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9
Q

Why are increasing levels of carbon dioxide and methane in the atmosphere a problem?

A
  • They have the potential to cause an enhanced greenhouse effect
  • It leads to global warming, which leads to melting ice caps, rising sea levels and climate change
  • Climate change causes floods and problems with farming and disease
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10
Q

How can greenhouse gas emissions be reduced?

A
  • Using fewer fossil fuels, by using renewable sources of energy such as biofuels instead
  • Using carbon capture technology to stop carbon dioxide from escaping when fuels are burnt
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11
Q

How can the effects of climate change be reduced?

A
  • Building flood defences
  • Planting different crops
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12
Q

What are some pollutants released by the combustion of fossil fuels?

A
  • Carbon monoxide
  • Sulfur dioxide
  • Oxides of nitrogen
  • Particulates
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13
Q

In what situation are carbon monoxide and particulates produced by fossil fuels?

A
  • Incomplete combustion
  • They are also sometimes produced by vehicle engines
  • Particulates are also produced by industrial processes
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14
Q

What problems does carbon monoxide cause?

A
  • It’s toxic
  • It’s also colourless, tasteless and odourless
  • It binds to haemoglobin in the blood, and therefore reduces its capability to carry oxygen
  • It causes drowsiness, breathing difficulties and even death
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15
Q

What problems do particulates cause?

A
  • They’re small particles
  • They can therefore settle in the lungs if breathed in, and cause breathing difficulties
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16
Q

How is sulfur dioxide produced?

A
  • Hydrocarbons contain sulfur impurities
  • The sulfur is oxidised so it forms sulfur dioxide gas
17
Q

How are oxides of nitrogen produced?

A
  • Nitrogen and oxygen do not normally react together
  • Temperatures in vehicle engines are high enough for them to react together to form nitrogen monoxide
  • Nitrogen monoxide is then oxidised in the air to form nitrogen dioxide
  • Together these 2 oxides of nitrogen are called NOx
18
Q

Why are acidic oxides bad for the environment?

A
  • Nitrogen dioxide and sulfur dioxide dissolve in water in clouds
  • They causes acid rain
19
Q

Why is acid rain a problem?

A
  • It kills trees
  • It kills living things in rivers and lakes
  • It damages stonework and corrodes metal
20
Q

What issue do atmospheric pollutants cause together?

A
  • They react together in sunlight to form a harmful photochemical smog
21
Q

How is fresh water made potable?

A
  • It is passed through a screen to remove large objects such as branches and leaves
  • A coarse filter bed made of sand and gravel removes large insoluble particles
  • Aluminium sulfate is added which causes fine particles to clump together and settle at the bottom in a sedimentation tank
  • A fine filter bed removes very small insoluble particles
  • Chlorine gas is added to kill harmful microorganisms
22
Q

How is seawater made potable, and why is this an issue?

A
  • It is distilled
  • This requires a lot of energy, so is not suitable for large amounts of water
  • It is therefore only used in countries where other options are unavailable, or energy resources aren’t expensive
23
Q

How is sewage water treated?

A
  • Screening and grit removal to remove large particles
  • Sedimentation; tiny particles settle out from the water and form sewage sludge
  • The sewage sludge is digested anaerobically by bacteria
  • The effluent (the liquid that was on top of the sewage sludge) is treated with aerobic bacteria