T9: chemistry of the atmosphere Flashcards
Why is there not a long of evidence for the early atmosphere?
Evidence for the early atmosphere is limited because of the long time scale of 4.6 billion years.
What are the different ‘phases’ in the theories for how the earth’s atmosphere has evolved?
1) volcanoes gave out gases
2) oceans, algae and green plants absorbed carbon dioxide
3) algae and green plants produced oxygen
What were the first billion years of earth’s history like?
Pretty explosive: the surface was covered in volcanoes that erupted and released a lot of gases (this is how we think the early atmosphere was formed).
What was the early atmosphere like?
The early atmosphere was probably mostly carbon dioxide and virtually no oxygen. This is quite like the atmospheres of Mars and Venus today.
How did volcanic activity change the atmosphere?
Volcanic activity released nitrogen which built up in the atmosphere over time as well as water vapour and small amounts of methane and ammonia.
What happened to the water vapour in the atmosphere?
condensed to form oceans.
What was the 3 things that cause the concentration of carbon dioxide in the atmosphere to decrease?
-oceans
-green plants and algae
-rocks
How did the concentration of carbon dioxide decrease due to oceans?
Lot son 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.
How did the concentration of carbon dioxide decrease due to green plants and algae?
Green plants and algae evolved and absorbed some of the carbon dioxide so that they could carry out photosynthesis.
What happened to marine animals (during phase 2)?
Later marine animals evolved as they formed shells and skeletons containing carbonates from the atmosphere.
What happens when plants, plankton and marine animals die?
- they fall to the seabed and get buried by layers of sediment.
- 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.
How did the concentration of carbon dioxide decrease due to rocks?
Some of the carbon these organisms (the evolved marine animals) took in from the atmosphere and oceans became locked up in rocks and fossil fuels after these organisms died.
What are the fossil fuels?
Things like coal, crude oil and natural gas that are made by this process are called fossil fuels.
How is crude oil and natural gas formed?
Formed from the deposits of plankton. These fossil fuels form reservoirs under the seabed where they get trapped in rocks.
What is coal and how is coal formed?
Coal is a sedimentary rock made from thick plant deposits.
What is limestone and how is it formed?
Limestone is also a sedimentary rock. It’s mostly made of calcium carbonate deposits from the shells and skeletons of marine organisms.
How did the concentration of oxygen change and why?
Increased as green plants and algae produced oxygen by photosynthesis: where plants use light to convert carbon dioxide and water into sugars.
When was oxygen first produced?
Algae first produced oxygen about 2.7 billion years ago and soon after this oxygen appeared in the atmosphere. Over the next billion years plants evolved.
What happened as oxygen levels changed?
As the oxygen levels/percentage built up in the atmosphere over time, more complex life (animal life) could evolve.
For the past 200 millions years, what has the atmosphere been like?
the proportions of different gases in the atmosphere have been much the same as they are today:
- about four-fifths (approximately 80%) nitrogen
- about one-fifth (approximately 20%) oxygen
- small proportions of various other gases(each only makes up less than 1% of the atmosphere) , including carbon dioxide, water vapour and noble gases.
What are the greenhouse gases and what do they do?
Carbon dioxide, methane and water vapour act as an insulating layer in the earth’s atmosphere- this, among other factors, allows the earth to be warm enough to support life.
What do all particles do?
All particles absorb certain frequencies of radiation/
Describe the greenhouse effect in terms of the interaction of short and long wavelength radiation with matter.
-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 directions; including back towards the earth.
- The long wavelength radiation is thermal radiation, so it results in warming of the surface of Earth.
What forms of human activity affect the amount of greenhouse gases in the atmosphere?
deforestation, during fossil fuels, agriculture and creating waste.
How does deforestation affect the amount of greenhouse gases in the atmosphere?
Fewer trees means less carbon dioxide is removed from the atmosphere via photosynthesis.
How does burning fossil fuels affect the amount of greenhouse gases in the atmosphere?
Carbon that was ‘locked up’ in these fuels is released as carbon dioxide.
How does agriculture affect the amount of greenhouse gases in the atmosphere?
More farm animals produce more methane through their digestive process.
How does creating waste affect the amount of greenhouse gases in the atmosphere?
More landfill sites and more waste from agriculture means more carbon dioxide and methane released by the decomposition of waste.
What has increasing carbon dioxide been linked to and why?
The earth’s temperature varies but recently the average temperature of the Earth’s surface has been increasing. Scientists agree, through peer pressure (so information is reliable) that extra carbon dioxide produced from human activity is causing this increase and that it will lead to CLIMATE CHANGE.
Why is it difficult to fully understand the earth’s climate?
because it is so complex (complex system) and there are so many variables that it is very hard to make a model that is not oversimplified.
What has not being able to fully understand the earth’s climate lead to?
speculation, particularly in the media- where stories may be biased or only some/part of the information is given.
What are the 4 dangerous consequences of climate change?
1) Higher global temperatures are causing the polar ice caps to melt, causing SEA LEVELS TO RISE. If sea levels keep rising, this will lead to increased flooding in costal areas and costal erosion.
2) Changes in rainfall patterns (amount, timing and distribution) are causing too much or too little water. This along with temperature changes may affected the ability of certain regions to produce food.
3) The frequency + severity of storms may also increase.
4) Changes in temperature + the amount of water available in different habitats are affecting wild species, leading to changes in their distribution.
What is carbon footprint?
The 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.
Why is measuring the total carbon footprint of something very difficult?
As the are so many different factors to count, e.g the emission released sourcing the parts, making it, using it and disposing it.
Why is a rough calculation of total carbon foot print still useful?
Can give a good idea of what the worst emitters are so that people can avoid them in the future.
How can the carbon footprint be reduced?
The carbon footprint can be reduced by reducing emissions of carbon dioxide and methane (greenhouse gases)
What are the 5 methods to reduce carbon footprint?
- renewable energy resources/ nuclear energy used instead of fossil fuels.
- use more efficient processes to conserve energy and cut waste.
- Governments could tax companies based on the amount of green house gases they emit.
- Governments can put a cap on emissions of all greenhouse gases that companies make- sell licence for emissions up to that cap.
- Technology captures CO2 produced by burning fossil fuels before it’s released into the atmosphere.
How would more efficient process reduce carbon footprint?
Lots of waste decomposes to produce methane, so this will reduce methane emissions.
How could Governments taxing companies based on the amount of green house gases they emit reduce carbon footprint?
taxing cars based on the amount of CO2 they emit over a set distance could mean that people choose to buy ones that are more fuel efficient and so less polluting.
How can the carbon dioxide captured by technology be stored?
stored deep underground in cracks in the rock such as old oil wells.
Why is making actions for carbon footprint reductions limited? (4)
- a lot of works to be done on alternative technologies that result in lower CO2 emissions.
- lots of governments worried the changes will impact economic growth of communities which could be bad for people’s well being (particularly for developing countries)
- Not all on board so hard to make international agreements to reduce emissions.
- Individuals in developed countries don’t want to make changes to their lifestyle and there isn’t enough educations provided about why the changes are necessary and how to make them.
Why does all not being on board with reducing carbon footprint make action limited?
Most countries don’t want to sacrifice their economic development if they think that others won’t do the same?
What do fossil fuels contain?
fossil fuels, such as crude oil and coal, contain hydrocarbons
What happens during combustion of fossil fuels?
The carbon and hydrogen in the hydrocarbons are oxidised so that carbon dioxide and water vapour are released into the atmosphere.
When does complete combustion occur?
When there is plenty of oxygen and all of the fuel burns.
When does incomplete combustion occur and what does it produce?
- if there is not enough oxygen, some of the fuel doesn’t burn
- solid particles (called particulates) of soot (carbon) and unburnt fuel are released and carbon monoxide is produced as well as CO2.
What are the problems caused by particulates in the air?
- If particulates are inhaled, they can get stuck in the lungs and cause damage, leading to RESPIRATORY PROBLEMS.
- They’re bad for the environment as they or the clouds they help to produce reflect sunlight back into space. This means that less light reaches the Earth causing GLOBAL DIMMING.
What are the problems caused by carbon monoxide?
- stops your blood from doing its proper job of carrying oxygen around the body.
- binds to the haemoglobin in your blood that normally carries O2 so less oxygen is able to be transported round your body.
- lack of oxygen in the blood can lead to fainting, a coma and even death.
- Carbon monoxide is a toxic gas. It is colourless and odourless and so is not easily detected.
How is sulfur dioxide released?
during the combustion of fossil fuels such as coal that contain sulfur impurities- the sulfur in the fuel become oxidised.
How can you test for sulfur impurities in a fuel?
by bubbling the gases from combustion through a solution containing universal indicator- if the fuel contain sulfur the gases will contain SO2 which will will dissolve to form an acidic solution and turn the universal indicator red.
How is 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).
What are the problems of sulfur dioxide and nitrogen oxides?
Sulfur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain.
How do sulfur dioxides and nitrogen oxides cause acid rain?
When these gases mix with clouds they form dilute sulfuric acid or dilute nitric acid which then falls as acid.
What are the problems of acid rain?
-kills plants
- damages buildings and states
- corrodes metal
