Studied by 0 people
chemistry paper 2 c9
(5.9.1) Describe the proportions of gases in the modern atmosphere
around 80% of N2
20% of O2
small quantities of CO2, H2O and noble gases
(5.9.1) Describe the earth’s early atmosphere and how it was formed
the earth was hot when it was formed
there were significantly volcanic activity
gases have been released from these volcanoes
these gases included CO2, N2, CH4, NH3, H2O
(5.9.1) How did the amount of oxygen in the atmosphere increase?
algae and plants made the atmospheric O2 by photosynthesis, which can be represented by: 6 CO2 + 6H2O arrow C6 H12 O6 + 6 O2
as the amount of O2 gradually increased, there were more plants which made more oxygen
(5.9.1) How did the amount of carbon dioxide in the atmosphere decrease?
some CO2 was dissolved in the oceans, where it reacted with metal ions to form insoluble carbonates such as CaCO3 or was taken in by animals to become a part of skeleton. When animals die, this becomes a sedimentary rock
some CO2 was used in photosynthesis to make oxygen
(5.9.2)What is the greenhouse effect? what are greenhouse gases? give egs
Greenhouse gases in the atmosphere maintain temperatures on earth high enough to support life
they allow short wavelength radiation from the sun to pass through the atmosphere the Earth’s surface, but absorb the outgoing long wavelength radiation from the earth causing an increase in temperature
Water vapour
carbon dioxide
methane
(5.9.2) Why is the greenhouse effect necessary for life?
Its a natural phenomenon. Without it, the earth would be too cold for life to exist
(5.9.1) How have human activities led to an increase in greenhouse gases
carbon dioxide- combustion and deforestation
methane- increased farming and decomposition in landfills
(5.9.2) What are the potential effects of global climate change? (6 effects)
sea level rise, may cause flooding and increased coastal erosion
more frequent and severe storms
changes in the amount, timing and distribution of rainfall
temperature and water stress for humans and wildlife
changes in the food- producing capacity of some regions
changes to the distribution of wildlife species
(5.9.2) What is a carbon footprint
the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event
(5.9.2) what actions can be taken to reduce a carbon footprint? (6 ways)
increased use of alternative energy supplies
energy conservation
carbon capture and storage (where CO2 is trapped in solvents and stored underground)
carbon taxes and licenses
carbon off-setting including through tree planting
carbon neutrality- zero net release
(5.9.2) What are the challenges faced with reducing a carbon footprint? (5 ways)
scientific disagreement over causes and consequences of global climate change
lack of public information and education
lifestyle changes (people don’t want to give up their cars)
economic considerations (it will cost money)
incomplete international cooperation
(5.9.3) What are the advantages of complete combustion?
less soot (carbon particulates) is made with complete combustion
more heat per gram of fuel is released with complete combustion
poisonous carbon monoxide is not produced with complete combustion
(5.9.3) how is pollution caused by combustion?
when a fuel burns, the gases released to the atmosphere include carbon dioxide, water vapour, carbon monoxide, sulphur dioxide and oxides of nitrogen
solid particles and unburned hydrocarbons may also be released that form particulates in the atmosphere.
(5.9.3) What are the issues regarding sulfur dioxide and oxides of nitrogen?
sulfur dioxides and oxides of nitrogen cause respiratory problems in humans and cause acid rain which damages plants and buildings
(5.9.3) what problems do particulates cause?
global dimming as it reduces the amount of sunlight which reaches the earth’s surface
they cause health problems for humans damaging the lungs
