C9- Chemistry Of The Atmosphere Flashcards
The proportion of gases in the atmosphere (4)
For 200 million years it has been the same as today:
• About four-fifths (around 80%) nitrogen
• About one-fifth (around 20%) oxygen
• small proportions of various other gases, including carbon dioxide, water vapour and noble gases
Theories about what was in the Earth’s early atmosphere (2)
- One theory suggests that during the first billion years Earth’s existence there was intense volcanic activity that released gases that formed the early atmosphere and water vapour that condensed to form the oceans
- The atmosphere was mainly made up of carbon dioxide with little or no oxygen gas
How was the atmosphere formed (theory)
• Volcanoes produced nitrogen which gradually built up in the atmosphere and there may have been small proportions of methane and ammonia
How has the atmosphere changed and developed over time (theory)
When the oceans formed carbon dioxide dissolved in the water and carbonates were precipitated producing sediments reducing the amount of carbon dioxide in the atmosphere
How was oxygen produced
- Through algae and plants via photosynthesis
- Algae first produced it about 2.7 billion years ago - soon after it appeared in the atmosphere
- Over the next billion years plants evolved and the percentage of oxygen gradually increased to a level that enabled animals to evolve
Equation for the production of oxygen (photosynthesis) (2)
6CO2 + 6H20 —> C6H12O6 + 6O2
Carbon dioxide + water —(light)> glucose + oxygen
Describe the main changes in the atmosphere over time
- Algae and plants decreased the percentage of carbon dioxide in the atmosphere by photosynthesis
- Carbon dioxide was also decreased by the formation of sedimentary rocks
How were sedimentary rocks formed
When plants, plankton and marine animals die, they fall to the sea bed and get buried by layers of sediment - over millions of years they become compressed and form sedimentary rocks such as limestone
How is coal made
- coal is a sedimentary rock
* it is made from plant deposits
How was crude oil and natural gas formed (2)
- formed from deposits of plankton
* these fossil fuels form reservoirs under the seabed when they get trapped in rocks
How is limestone formed (3)
- Limestone is a sedimentary rock
- Mostly made up of calcium carbonate
- deposits from the shells and skeletons of marine organisms
What do greenhouse gases do
Maintain temperatures on Earth high enough to support life
Examples of greenhouse gases (3)
- Water vapour
- Carbon dioxide
- Methane
Describe the greenhouse effect in terms of the interaction of short and long wavelength radiation with matter (2)
- short wavelengths of visible light from the sun pass through a transparent medium and are absorbed
- but the longer wavelengths of the infrared re-radiation from the heated objects are unable to pass through that medium
State two human activities that increase the amounts of each of the greenhouse gases carbon dioxide and methane
- Burning fossil fuels
* Cutting down forests
What is peer reviewed evidence
This is the evidence that has been throughly checked by other scientists
Why is peer reviewed evidence important
- To make sure that evidence is reliable
* reduce the risk of potential faulty evidence
Why is it difficult for scientists to prove their theories about greenhouse gases
Because the atmosphere is enormous and complex as well as many variables
4 potential effects of global climate change
- Polar ice caps melting - causing a rise in sea level, increased flooding and costal erosion
- Changes in rainfall patterns - may cause some regions to get too little or too much water which can impact the ability of regions to produce food
- Frequency and severity of storms may also increase
- Differences in distributions due to temp and amount of water change
Carbon footprint
Is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event
Ways of reducing carbon footprint (5)
- Using renewable energy sources or nuclear energy instead of fossil fuels
- cutting waste and improving efficiency - waste releases methane when decomposed
- Government could tax companies or individuals on the amount of greenhouse gases they emit
- Governments could put caps on emissions of all greenhouse gases that companies make
- Carbon store and carbon capture
Why are actions to reducing carbon footprints limited (3)
- A lot of governments are worried about the impact on economic growth of communities which effect peoples well being
- Difficult to make international agreements - countries don’t want to sacrifice economic development if they think that others won’t do the same
- Individuals not changing their lifestyle - perhaps due to not enough education about the importance of it
How is carbon monoxide and soot produced when burning fuels (2)
- When there’s not enough oxygen some of the fuel doesn’t burn (incomplete combustion)
- Under these conditions soot and carbon monoxide is produced
How is sulfur dioxide produced when burning food
• Is released during the combustion of fossil fuels that contains sulfur impurities - the sulfur becomes oxidised
How are nitrogen oxides produced by burning fuels (2)
- Are created from a reaction between nitrogen and oxygen caused by the heating of the burning
- This can occur in the internal combustion of fossil fuels
What is the major source of atmospheric pollutants?
The combustion of fuels
What do most fuels including coal contain (2)
- Carbon and/or hydrogen
* May also contain sulfur
What gases are released into the atmosphere when a fuel is burned (5)
- Carbon dioxide
- Water vapour
- Carbon monoxide
- Sulfur dioxide
- Nitrogen oxides
How are particulates formed in the atmosphere
By solid particles and unburned hydrocarbons being released
What is carbon monoxide (2)
- Is a toxic gas
* Colourless and odourless - so is not easily detected
What do oxides of nitrogen and sulfur dioxide cause (2)
- respiratory problems in humans
* Cause acid rain
What do particulates cause (2)
- Global Dimming
* Health problems for humans
