Chemistry of the atmosphere Flashcards
Have theories for how the Earth’s atmosphere evolved changed over time?
Yes- the theories have changed a lot over the years.
Why have the theories on how the Earth’s atmosphere has evolved changed over time?
Hard to gather evidence from such a long time period and from so long ago (4.6 billion years).
What is the first phase of the evolution of the atmosphere?
Volcanoes gave out gases.
What was the surface of the Earth like in the planet’s first billion years?
Covered in volcanoes that erupted and released lots of gasses. We think this was how the early atmosphere was formed.
What gasses were found in the early atmosphere?
Probably mostly carbon dioxide, with virtually no oxygen.
Nitrogen was also release by volcanic activity and built up in the atmosphere over time.
Water vapour
Small amounts of methane and ammonia
What was the Earth’s early atmosphere similar to?
The atmospheres of Mars and Venus today.
What was the second phase of the evolution of the atmosphere?
Oceans, algae and green plants absorbed carbon dioxide.
What did the water vapour in the early atmosphere do?
It condensed and formed the oceans.
How was lots of carbon dioxide removed from the early atmosphere?
It dissolved in the oceans.
What happened to the carbon dioxide from the early atmosphere that was dissolved in oceans?
Went through a series of reactions to form carbon precipitates that formed sediments on the seabed.
What happened when green plants and algae evolved?
They absorbed some of the carbon dioxide in the early atmosphere so they could carry out photosynthesis.
What was contained inside the shells and skeletons of the marine animals that evolved?
They contained carbonated from the oceans.
What happened to some of the carbon that organisms took in from the early atmosphere and oceans?
The carbon became locked up in rocks and fossil fuels after the organism died.
What happened when plants, plankton and marine animals die?
They fall to the seabed and get buried by layers of sedimentary.
Over millions of years, they become compressed and form sedimentary rocks, oil and gas- trapping the carbon within them and helping to keep carbon dioxide levels in the atmosphere reduced.
Fossil fuels are made like this e.g. coal, crude oil and natural gas.
How is crude oil and natural gas formed?
From the deposits of plankton. These types of fossil fuels form reservoirs under the seabed when they get trapped in rocks.
What is coal?
A sedimentary rock made from thick plant deposits.
What is limestone?
A sedimentary rock.
Mostly made of calcium carbonate deposits from the shells and skeletons of marine organisms.
What is the third phase of the evolution of the atmosphere?
Green plants and algae produced oxygen
How did green plants and algae produce oxygen (in the early atmosphere)?
By absorbing CO2 and doing photosynthesis.
What is the equation for photosynthesis?
What evolved first- plants or algae?
Algae- about 2.7 billion years ago.
Over the next billion years or so, green plants also evolved.
What happened as oxygen levels built up in the atmosphere over time?
More complex life like animals could evolve.
What happened to the Earth’s atmosphere about 200 million years ago?
It reached a composition similar to what it is today. About:
80% nitrogen
20% oxygen
Small amounts of carbon dioxide, noble gasses and water vapour.
What are some examples of greenhouse gasses?
CO2
Methane
Water vapour
What do greenhouse gasses do?
Act like an insulating layer in the Earth’s atmosphere.
One of the factors that allow the Earth to be warn enough to support life.
All particles absorb…
certain frequencies of radiation.
What type of radiation does greenhouse gasses absorb?
Not the incoming short wavelength radiation from the sun but the long wavelength radiation that gets reflected back off the Earth.
What do the greenhouse gasses do with the long wavelength radiation they absorb?
Re-radiate it in all directions- including back towards the 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 are some forms of human activity that affects the amount of greenhouse gases in the atmosphere?
Deforestation
Burning fossil fuels
Agriculture
Creating waste
How does deforestation affect the amount of greenhouse gasses in the atmosphere?
Fewer trees means less CO2 is removed from the atmosphere vis photosynthesis.
How does burning fossil fuels affect the amount of greenhouse gasses in the atmosphere?
Carbon that was ‘locked up’ in these fuels is released as CO2.
How does agriculture affect the amount of greenhouse gasses in the atmosphere?
More farm animals produce more methane through their digestive processes.
How does creating waste affect the amount of greenhouse gasses in the atmosphere?
More landfill sites and more waste from agriculture means more CO2 and methane released by decomposition of waste.
What is happening recently with the average temperature of the Earth’s surface?
It’s been increasing
Does the Earth’s temperature vary naturally/
YES
What is the extra carbon dioxide from human activity causing?
An increase in the Earth’s surface temperature. This will lead to climate change.
Why is it hard to fully understand the Earth’s climate?
Because it’s so complex and there are so many variables, that it’s very hard to made a model that isn’t oversimplified.
What could an increase in global temperatures lead to?
Polar ice caps melting, causing:
A rise in sea levels
Increased flooding in costal areas
Costal erosion
What could changes in rainfall patterns cause?
Some regions may get too much or too little water. This, along with changes in temperature, may affect the ability of certain regions to produce food.
What would happen to storms as a result of climate change?
Their frequency and severity may increase.
What could happen as a result of the changes in temperature and the amount of water available in a habitat?
May affect wild species, leading to differences in their distribution.
What are carbon footprints?
A measure of the amount of carbon dioxide and other greenhouse gasses released over the full life cycle of something.
This can be a service e.g. school bus, an event e.g. the Olympics or a product e.g. a toastie maker.
Why is measuring the total carbon footprint of something really hard/impossible?
There are so may different factors to consider e.g. you would have to count the emissions released as a result of sourcing all the parts of a product, in making it, in using it and when you dispose of it.
What are some ways you can reduce a thing’s carbon footprint?
Anything that reduces the amount of greenhouse gasses given out by a process will also reduce its carbon footprint:
. Using renewable/nuclear energy sources instead of fossil fuels
. Using more efficient processes
. Governments taxing individuals and companies
. Governments putting a cap on emissions
. Carbon capture and storage
How can using more efficient processes reduce carbon footprints?
This could conserve more energy and cut waste. Lots of waste decomposes to release methane, so this will reduce methane emissions.
How can the govt. taxing companies or individuals reduce carbon footprints?
The taxing would be based on the amount of greenhouse gasses they emit e.g. taxing cars based on the amount of carbon dioxide they emit over a set distance could mean that people choose to buy cars that are more fuel-efficient and so less polluting.
How can the govt. putting a cap on emissions reduce carbon footprints?
They could put a cap on emissions of all greenhouse gases that companies make- then sell licences for emissions up to that cap.
How can carbon capture and storage reduce carbon footprints?
The technology can capture the CO2 produced by burning fossil fuels before it’s released into the atmosphere- it can then be stored deep underground in cracks in the rock such as old oil wells.
Why is it hard to cut emissions?
. There’s a lot of work to be done on alternative technologies that result in lower CO2 emissions
. A lot of govts. are worried that making these changes will impact on economic growth of communities
. Not every county is on board- hard to make international agreements to reduce emissions
. Hard for individuals in developed countries to make changes
Why are govts worried about changes that could impact the economic growth of some communities?
This could be bad for people’s well-being. This is particularly important for countries that are still developing.
Why is it hard to make international agreements to reduce greenhouse gas emissions when not every country is on board?
Most countries don’t don’t want to sacrifice their economic development if they think that others won’t do the same.
Why is it hard to get people in developed countries to change their lifestyle?
They don’t want to.
There isn’t enough education provided about why the changes are necessary and how to make them.
What are some other gasses (apart from CO2) that are released when fossil fuels burn?
Oxides of nitrogen
Sulfur dioxide
Carbon monoxide
What do fossil fuels (e.g. crude oil and coal) contain?
Hydrocarbons
What happens during the combustion of fossil fuels?
The carbon and hydrogen in these compounds are oxidised so that carbon dioxide and water vapour are released into the atmosphere.
What does combustion of fossil fuels release?
Gasses and particles
What is complete combustion?
When there’s plenty of oxygen and all the fuel burns.
What is incomplete combustion?
If there’s not enough oxygen and some of the fuel doesn’t burn.
What happens under the conditions of incomplete combustion?
Particulates of soot (carbon) and unburnt fuel are released and carbon monoxide can be produced as well as carbon dioxide.
What problems can particulates in the air cause?
. If inhaled, they can get stuck in the lungs
. Bad for the environment
Why is particulates getting stuck in our lugs dangerous?
They can cause damage, which can then lead to respiratory problems.
Why are particulates bad for the environment?
They themselves, or the clouds they help to produce, reflect sunlight back into space. This means less light reaches the Earth- causing global dimming.
Why is carbon monoxide (CO) really dangerous?
It can stop your blood from doing its proper job of carrying oxygen around the body.
How can CO stop your blood from carrying oxygen around your body?
CO binds to the haemoglobin in your blood that normally carries O2- so less oxygen is able to be transported round your body.
What can a lack of oxygen in the blood lead to?
Fainting, a coma or even death.
What does carbon monoxide look like?
It is colourless and odourless, so it’s very hard to detect . This makes it even more dangerous.
When is sulfur dioxide (SO2) released?
During the combustion of fossil fuels (e.g. coal) that contain sulfur impurities. The sulfur in the fuel becomes oxidised.
How are nitrogen oxides created?
From a reaction between the nitrogen and oxygen in the air, caused by the heat of the burning. This can happen in the internal combustion engines of cars for example.
What happens when SO2/nitrogen oxides mix with the clouds?
They form dilute sulfuric acid or dilute nitric acid. This then falls as acid rain.
What can acid rain do?
Kill plants
Damage buildings and statues
Corrode metal
How can SO2 and nitrous oxides be bad for human health?
They cause respiratory problems if they’re breathed in.
How can you test for sulfur impurities in a fuel?
By bubbling the gasses from combustion through a solution containing universal indicator. If the fuel contains sulfur, the gases will contain SO2. This will form sulfuric acid and turn the universal indicator red.
