Chemistry C9 Flashcards
Percentage of gases in present day?
Nitrogen=78%
Oxygen=20%
CO2=0.04%
Other gases=1.96%
What gases did the earths early atmosphere consist of?
- CO2
- Ammonia
- Methane
- Water vapour
How did the levels of these early atmosphere change?
decrease/increase
- Water vapour decreased as it rained to make oceans
- CO2 decreased (dissolved into oceans, locked up in rocks and photosynthesis)
- Oxygen increased(photosynthesis)
3 greenhouse gases
- CO2
- water vapour
- methane
How did CO2s structure lead to global warming?
O = C = O
These bonds absorb infrared radiation
Global warming/ climate change effects
- ice melting (polar bears drowning)
- sea levels rising (flooding)
- plants dying/animals dying(humans cant eat)
How has the graph
y=CO2 levels
x=Time(years)
changed over time
Always increasing- even steeper in recent years
Human activities increasing CO2 levels
- burning fossil fuels for electricity
- deforestation as trees cant take in co2
- transportation (reliance on petrol cars)
What is carbon footprint?
How much carbon your daily activities contribute to the atmosphere
2 ways to improve your carbon footprint
- walking instead of driving
- eating local food vs food that has had to travel long distances
5 pollutants/effects of these
Sulfur dioxide- acid rain (kills animals eg. fish, kills plants and destroys statues eg. limestone)
Carbon- smog/global dimming (mainly in developing countries)
Water vapour- warming of the planet
Carbon monoxide- toxic
Nitrogen oxides- smog/acid rain
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’s temperature so it is warm enough to support 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 greenhouse 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
How do carbon particulates form during combustion of fuels
Carbon from the fuel doesn’t react with oxygen
What problems are associated with carbon monoxide?
It is a toxic gas that can kill, it is hard to detect as it is colourless and odourless
What problems are associated with sulphur dioxide and nitrogen oxides?
They cause acid rain as well as respiratory problems
What problems are associated with carbon particulates?
They cause global dimming and irritate the lungs
