The Atmosphere Flashcards
what percentage of the atmosphere is nitrogen
78%
what percentage of the atmosphere is oxygen
21%
what do the rest of the gases in the atmosphere consist of
small proportions of other gases eg carbon dioxide , water vapour , noble gases eg argon
what is a theory about the Earth’s early atmosphere and how it was formed
Scientists think that during the first billion years, there was intense volcanic activity
- the volcanoes released the gases that formed the atmosphere ( eg water vapour) AND a lot of carbon dioxide
- As the earth cooled, the water vapour condensed to form the oceans
what gases were prominent in the early stage of earth’s atmosphere
consisted mainly of carbon dioxide with little or no oxygen
what planets were representative of earth’s early atmosphere
mars and venus
what substances did the volcanoes release
- water vapour, carbon dioxide , nitrogen , small amounts of methane and ammonia
what are the differences between the earth’s early atmosphere and the current earth atmosphere
- early atmosphere contained large amounts of carbon dioxide but atmosphere today only contains a small amounts
- early atmosphere contained very little/no oxygen whereas today 21% of the atmosphere is oxygen
how did the levels of carbon dioxide reduced in the atmosphere
- water vapour from volcanoes condensed to form oceans = carbon dioxide dissolved in oceans to form weak acid = this reacted with minerals in sea to form precipitates - over time this formed sediments of carbonate rock on the sea bed
- some of the carbon dioxide in sea was used to make corals and shells of organisms - when these died they formed the sedimentary rock limestone = removed carbon dioxide from atmosphere
- through photosynthesis of plants the carbon dioxide is taken in and trapped in fossil fuels
how have the levels of oxygen increased in the atmosphere
-Algae and plants produced the oxygen that is now in the atmosphere by photosynthesis
- 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 and the percentage of oxygen gradually increased to a level that enabled animals to evolve.
how is coal formed
Coal is formed from remains of ferns and trees
- when they die in marshy wetlands, they do not decompose, due to lack of oxygen and acidic conditions, preventing bacteria from carrying out decomposition
- over time, plant remains are covered with sediment and compressed
- high temperatures and pressure creates coal
how is crude oil formed
- crude oil is formed from plankton
- when they die, they settle in the mud on the seabed
- if oxygen is not present, they do not decompose
- over time, they are compressed by sediments
- heat and pressure convert them into crude oil
how is natural gas formed
natural gas is mainly the hydrocarbon methane
- natural gas is found near deposits of oil
- this is because natural gas is formed from plankton and when they die their remains sink to the bottom where they were buried under sediments. The lack of oxygen prevented oxidation from occurring. Over millions of years, heat and pressure turned the remains of the organisms into crude oil and natural gas.
all fossil fuels contain trapped carbon, part of the carbon dioxide taken in by photosynthesis
what are 4 examples of greenhouse gases
- water vapour
- carbon dioxide
- methane
- nitrous oxide
describe how the greenhouse effect works
- energy from the sun travel to earth as short wavelength radiation (ultraviolet and visible light)
- some radiation reflects back into space, but most pass easily through the earth’s atmosphere
- this is because short wavelength radiation do not interact strongly with gas molecules in the atmosphere
- energy of radiation is absorbed when reaching the surface of the earth
- the surface then radiates the energy as long wavelength radiation (infrared)
- some of this radiation interact with greenhouse gas molecules, and the energy is absorbed
- this trapped energy causes the temperature of the atmosphere to increase
what would life be like without greenhouse effect
the earth would be too cold for organisms to survive
what are the human activities that are increasing carbon dioxide
carbon dioxide is increasing as we burn fossil fuels
- these include coal for electricity, petrol and diesel to power cars, and gas for homes
- carbon dioxide is normally absorbed by trees
- however, they are being destroyed by deforestation. or being burnt, releasing large amounts of carbon dioxide
what are the human activities increasing methane
methane is released in agriculture
- this includes growing rice in flooded paddy fields
- it is also released when cattle (cows) pass wind
- this causes levels of methane to increase
what are the effects of climate change
- rising temperatures will increase melting ice sheets and glaciers, = increased sea levels
- increased sea levels = lead to more flooding of low-land areas
- more severe weather, such as storms
- change distribution of animals, such as insects, and insect-born diseases, such as malaria
- affects crop growth due to sudden changes in weather
what
what is peer review
form of detecting false claims or bias by using multiple sources of evidence from other
what is carbon footprint
the total amount of carbon dioxide and other greenhouse gases, emitted over the full life cycle of a product, service, or event
how can carbon footprint be reduced
- Insulating homes and turning down the heating can reduce carbon dioxide emissions
- using public transport such as buses and trains = reduces carbon dioxide emission
- this can be reduced by switching to renewable sources and reducing the amount of electricity used in homes = reduces carbon dioxide emissions
what are the problems with reducing carbon footprint
- Most solutions are expensive, and people are reluctant to pay
- Some are also inconvenient, as people prefer driving in cars than public transport
- lack of public information and education
- some people are not willing to change their diets and not eat meat
how can methane levels be reduced
- methane can be reduced by buying and eating less beef and diary products, so there is less cattle grazing
- trapping and burning methane from landfills can be used to produce electricity
what are problems that people have of methane levels being reduced
- Some people are not willing to change diets and not eat meat
- trapping and burning methane is expensive
what is a fuel
material that is burned to releases energy when they are combusted (burnt) eg heat or power
what are 2 examples of fuels
coal and hydrocarbons
how do fuels release energy
when the fuels are combusted
What is coal used for
used to generate electricity in power stations
what are hydrocarbon used for
used to power vehicles
What elements are most commonly found in most fuels
carbon and hydrogen
What happens when fuel is burned
the carbon and hydrogen atoms react with oxygen in the air, and are oxidised
- this forms the greenhouse gases carbon dioxide and water vapour
what is the reaction and the equation for the combustion of methane
methane + oxygen –> carbon dioxide and water
where is methane found and what is methane used for
- Found in natural gas and is used to heat homes up
what is carbon monoxide
toxic gas with no colour or smell
what element does coal contain
sulfur
what happens when coal is burned
sulfur atoms are oxidised to form sulfur dioxide
what is the symbol equation for the oxidation of sulfur
S (s) + 02 (g) –>SO2 ( g)
What gas is produced in the engines
oxides of nitrogen
what happens to the nitrogen in the engines
high temperatures cause nitrogen and oxygen from the air to react to produces a range of different molecules so they are all called oxides of nitrogen ( NOx)
what is the symbol equation for the reaction of nitrogen and oxygen
N2 (g) + O2 (g) –> NOx ( g)
What issues do nitrogen and sulfur cause
- Respiratory issues in humans
- they dissolve in rainwater and cause acid rain = damages trees and corrodes buildings made from limestone
what are particulates
particles of carbon ( soot ) and unburned hydrocarbons
what issues to particulates cause
- can damage human health, eg increases risk of heart disease and lung disease
- reduces amount of energy from the sun that reaches the earth’s surface = resulting in global dimming
what are the advantages of complete combustion
- less soot is made
- more heat per gram of fuel is released
-poisonous carbon monoxide isn’t produced
