C9 Chemistry of the atmosphere Flashcards
What is composition of the atmosphere?
Approximately 80% Nitrogen, 20% Oxygen and small amounts of CO2,water vapour and Nobel gases
What was the composition of the earth’s early atmosphere?
Lots of carbon dioxide and water vapour from volcanic eruptions and small amounts of methane and ammonia
How did the level of water vapour reduce?
The earth cooled so the water vapour condensed and formed oceans
Give 2 ways the level of CO2 decreased
The CO2 dissolved in oceans and formed sedimentary rocks such as limestone. Plants evolved and photosynthesised which uses CO2 and produces O2
Why are greenhouse gases important for life on earth?
They maintain the earth so they are high enough to maintain life
Name three greenhouse gases
Methane, water vapour and carbon dioxide
How do greenhouse gases maintain the earth’s temperature?
Short wavelength radiation from the sun is transmitted through the atmosphere and absorbed by the earth. It is re-emitted from the earth at a longer wavelength which is absorbed by the green house gases.
How have humans contributed to CO2 levels rising?
Deforestation of trees reducing photosynthesis, burning of fossil fuels
How have humans contributed to methane levels rising?
Intensive cattle farming, rice paddy fields and land fill sites
Why is it difficult to model the effects of climate change?
There are many factors that effect it so it’s very complicated to predict
What is a problem with using simplified models for climate change?
It may be only be based on part of the evidence and be biased
Why is it important that data is peer-reviewed?
To know it has been checked by other scientists and that they agree with the conclusions
What are the implications of global temperature increases from climate change?
Floods, droughts, tornados/hurricanes, ice caps melt and sea level rise.
What does the term carbon footprint mean?
The total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event
How can people reduce their carbon footprint?
Use less energy, use renewable energy, offset their emissions by planting trees, stop eating beef and lamb, use biofuels.
Why might individual actions to reduce carbon emissions be limited?
The inconvenience or cost of these actions. Also individuals may feel they make little impact and governments or industry should fix this
What elements do most fuels contain?
Carbon and or hydrogen and may contain sulphur impurities
What are the products of complete combustion?
Carbon dioxide and water
What are the products of incomplete combustion?
Carbon monoxide, carbon particulates and water
When does incomplete combustion occur?
If there is a limited amount of oxygen
How does carbon dioxide form during combustion?
Carbon from the fuel reacts with oxygen from the air by complete combustion
How does carbon monoxide form during combustion?
Carbon from the fuel reacts with oxygen from the air by incomplete combustion
How does sulphur dioxide form during combustion?
Sulphur impurities in the fuel react with oxygen from the air
How do nitrogen oxides form during combustion of fuels?
Nitrogen from the air reacts with oxygen from the air inside a hot car engine
