TOPIC 9 - CHEMISTRY OF THE ATMOSPHERE Flashcards
What is phase one of the evolution of the atmosphere?
Volcanoes gave out gases.
The early atmosphere was formed from from volcanoes that covered the earth and erupted and released lots of gases.
The early atmosphere was probably mostly carbon dioxide, with virtually no oxygen.
Volcanic activity also released nitrogen, which built up in the atmosphere over time, as well as water vapour and small amounts of methane and ammonia.
What is phase two of the evolution of the atmosphere?
Oceans, Algae and Green Plants absorbed carbon dioxide.
When water vapour in the atmosphere condensed it formed oceans.
Lots of carbon dioxide was removed from the early atmosphere as it dissolved in the oceans. This dissolved carbon dioxide then went through a series of reactions to form carbonate precipitates that formed sediments on the seabed.
Green plants and algae evolved and absorbed some of the carbon dioxide so that they could carry out photosynthesis.
Later, marine animals evolved and their shells and skeletons contained carbonates from the Ocean.
Some of the carbon these organisms took in from the atmosphere and oceans became locked up in rocks and fossil fuels after the organisms died.
What is phase three of the evolution of the atmosphere?
Green plants and algae produced oxygen.
Produced oxygen by photosynthesis.
Algae evolved first, followed by green plants.
As oxygen built up in the atmosphere over time, more complex life, like animals, could evolve.
Name some greenhouse gases?
Carbon dioxide, methane, water vapour.
Explain the greenhouse effect?
All particles absorb certain frequencies of radiation. Greenhouse gases don’t absorb the incoming short wavelength radiation from the sun - but they do absorb the long wavelength radiation that gets reflected back off the earth. Then they re-radiate it in all direction - including back towards Earth. The longwave radiation is thermal radiation, so it results in the warming of the surface of the Earth. This is the greenhouse effect.
What forms of human activity affects the amount of carbon dioxide in the atmosphere?
Deforestation - less co2 is removed via photosynthesis.
Burning fossil fuels - carbon that was locked up in these fuels is released as co2.
Agriculture - more farm animals produce more methane through their digestive processes.
Creating waste - more landfill sites and more waste from agriculture means more co2 and methane released by decomposition of waste.
What are some of the consequences of climate change?
Polar ice caps melting - causing a rise in sea levels, increased flooding in coastal areas and coastal erosion.
Changes in rainfall patterns may cause some regions to have too little or too much water. This, along with changes in temperature, may affect the ability of certain regions to produce food.
The frequency and severity of storms may increase.
Changes in temperature and the amount of water available in a habitat may affect wild species, leading to differences in their distribution.
What is your carbon footprint?
A measure of the amount of carbon dioxide an other greenhouse gases released over the full life cycle of something. This can be a service e.g. the school bus, an event e.g. The Olympics, a product e.g. a toaster.
What factors have to be considered when measuring a carbon footprint?
You would have to count the emissions released as a result of sourcing all the parts of your object and in making it, and then the emissions produced when you actually use it and finally dispose of it.
How can you reduce carbon footprints?
Use renewable energy sources or nuclear energy instead of fossil fuels.
Use more efficient processes that conserve more energy and cut waste
Governments could tax companies or individuals based on the amount of greenhouse gases they emit e.g. taxing cars based on the amount of carbon dioxide they emit over a set distance could mean that people chose to buy ones that are more fuel-efficient, and so less polluting.
Governments can also put a cap on emissions of all greenhouse gases that companies make - then sell licenses for emissions up to that cap.
There is also technology that captures the co2 produced by burning fossil fuels before it is released into the atmosphere - it can then be stored deep underground in cracks in the rock such as old oil wells.
Why can reducing carbon footprints be difficult?
There is still lots of work to be done on alternative technologies that result in lower co2 emissions.
Governments worry that making these changes will impact their economic growth. This is particularly important for countries that are still developing.
Because not everyone is on board, it is difficult to make international agreements. Most countries don’t want to sacrifice their economic development if they think that others won’t do the same.
Some people don’t make lifestyle changes because they aren’t educated about why it is important.
How does the combustion of fossil fuels release gases and particles?
Fossil fuels, such as crude oil and coal, contain hydrocarbons. During combustion, the carbon and hydrogen in these compounds are oxidised so that carbon dioxide and water vapour are released into the atmosphere.
When there is plenty of oxygen, all the fuel burns - this is called complete combustion.
If there is not enough oxygen, some of the fuel doesn’t burn - this is called incomplete combustion. Under these conditions, solid particles (particulates) of soot (carbon) and unburnt fuel are released and carbon monoxide can be produced as well as carbon dioxide.
What problems do particulates in the air cause?
If they are inhaled, they can get stuck in the lungs and cause damage. This can lead to respiratory problems.
They are also bad for the environment - they themselves, or the clouds they help produce, reflect sunlight back into space. This means that less light reaches the Earth - causing global dimming.
What problems does carbon monoxide cause?
Very dangerous as it stops blood from carrying oxygen around the body. It does this by binding to haemoglobin in your blood that normally carries oxygen - so less oxygen is able to be transported round your body.
A lack of oxygen in the blood can lead to fainting, a coma, or even death.
Carbon monoxide doesn’t have any colour or smell, so it is very hard to detect, making it even more dangerous.
When is sulfur dioxide released?
During the combustion of fossil fuels , such as coal, that contain sufur impurities. - the sulphur in the fuel becomes oxidised.
