C9: Chemistry of the atmosphere Flashcards
Describe the proportions of gases in the modern atmosphere
- around 78% of N2 (Nitrogen)
- 21% of O2 (Oxygen)
- small quantities of carbon (CO2), argon
Describe the Earth’s early atmosphere and how it was formed
a) It may have consisted of mainly CO2 with little to no oxygen
b) There was intense volcanic activity that released gases that formed the early atmosphere
- these gases included C02 , N2 , CH4
Explain why evidence for the early atmosphere is limited
- Evidence is limited because of the time scale of 4.6 billion years
State which planets have similar atmospheres to Earth’s very early atmosphere
- Mars
- Venus
How did the amount of oxygen in the atmosphere increase?
- Algae & plants produced the O2
that is now in the atmosphere by photosynthesis - Over the next billion years plants evolved and the % oxygen gradually increased to a level that enabled animals to evolve
State when oxygen first appeared in the atmosphere
about 2.7 billion years ago
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 CaC03
- the formation of sedimentary rocks that by the production of fossil fuels from the
remains of dead plants and animals when they decayed
What is the greenhouse effect?
Short wavelength radiation from the sun is absorbed by the earth
- the atmosphere absorbs and reflects some radiation
- energy is emitted by the earth as long wave radiation
- greenhouse gases in the atmosphere absorb the long wave radiation, trapping the energy and warming the earth
List four greenhouse gases
- water vapor, carbon dioxide, methane, nitrous oxide
Describe the role of greenhouse gases in supporting life on Earth
- greenhouse gases maintain temperatures on Earth high enough to support life
State which greenhouse gases are produced by human activity and how
carbon dioxide - combustion and deforestation
methane - increased farming and decomposition in landfills
Describe five effects of global climate change
- sea level rising causing flooding and coastal erosion
- extreme weather events (frequent storms)
- changes to ecosystems and habitats
- changes in the amount and time of rainfall
- temperature and water stress for humans and wildlife
Define the term ‘ carbon footprint’
The total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event
What actions can be taken to reduce a carbon footprint
- increased use of alternative energy supplies
- carbon off-setting (through tree planting)
- carbon taxes and licenses
What are the problems of reducing the carbon footprint?
- scientific disagreement over causes and consequences of global climate change
- economic considerations
- lifestyle changes
State a major source of atmospheric pollutants
the combustion of fuels
State the gases released into the atmosphere when a fuel is burned and how does this cause pollution
- carbon dioxide
- water vapor
- carbon monoxide
- Sulphur dioxide
- solid particles and unburned hydrocarbons may also be released forming particulates in the atmosphere
State what most fuels contain
- carbon, hydrogen and also contain more sulphur
Describe how carbon monoxide is produced by burning fuels
incomplete combustion of fuels
Describe how soot (carbon particles) can be produced by burning fuels
incomplete combustion of fuels especially in diesel engines
Describe how sulphur dioxide is produced by burning fuels
sulphur impurities in the fuel react with oxygen from the air
Describe how oxides of nitrogen are produced by burning fuels
nitrogen in the air is heated near an engine and it reacts with oxygen
Give 3 advantages of complete combustion
- less soot (carbon particulates ) is made
- more heat per gram of fuel is released
- poisonous carbon monoxide is not produced
Describe what the effects of sulphur dioxide and oxides of nitrogen cause
- causes acid rain damaging plants and buildings
- causes respiratory problems in humans
Describe what particulates (soot and unburnt hydrocarbons) case
- cause global dimming reducing the amount of sunlight that reaches the Earth’s surface
- respiratory problems and could cause cancer
Describe a key property of carbon monoxide and explain why it is not easily detected
- it is a toxic gas
- it is colorless and odorless
Glucose is produced when algae photosynthesise.
Name two naturally occurring polymers produced from glucose. (2)
starch
1
cellulose
Glycine reacts by condensation polymerisation to produce a polypeptide
and one other substance.
Name the other substance produced (1)
water
