Chemistry of the atmosphere Flashcards
what happened during the first billion years of Earth
- no plant or animal life
- lots of volcanic activity which released
* mostly CO2
* water vapour ( condenses to form seas)
* small proportions of methane and ammonia
* nitrogen (gradually built up in the atmosphere)
What happened after 2.7 billion years
- water vapour condenses to form seas
- lots of carbon dioxide dissolved in the ocean
- the carbon in carbon dioxide becomes locked up in sedimentary rocks formed from the shells and skeletons of marine organisms
- Green plants and algae evolve
what happened when carbon dioxide dissolved in the ocean
- carbon precipitated producing sediments, reducing the amount of carbon dioxide in the atmosphere
the proportion of gases in the atmosphere have been more or less the same for about 200 million years.
what is the proportion of gases in the atmosphere today?
4/5 nitrogen (78%)
1/5 oxygen (21%)
small proportions of CO2 (0.04%), argon, water vapour and other noble gases
what caused an increase in oxygen levels?
- Algae and plant photosynthesise
(6CO2 + 6H2O = 6O2 +C6H12O6) - Algae gist started producing oxygen about 2.7 billion years ago
- Over the next billion years, plants evolved and the amount of oxygen increased
- eventually, the level of oxygen in the atmosphere increased enough to allow animals to evolve
what happened when green plants and algae evolved?
- CO2 is reduced as the plants take it in and give out oxygen
- microorganisms that can’t tolerate oxygen are killed off
- nitrogen is also produced by bacteria removing nitrates from decaying plant material
what caused a decrease in CO2 levels
- photosynthesis
- carbon becomes locked up in sedimentary rocks (e.g limestone) and fossil fuels ( e.g crude oil, coal and natural gases)
- the reaction between carbon dioxide and seawater which produces insoluble carbonates that are deposited as sediment and soluble hydrogen carbonates.
how is limestone formed?
Limestone contains calcium carbonate and can be formed from the shells and skeletons of sea creatures
How is coal formed?
- a sedimentary rock
- formed from plant deposits that were buried and compressed over millions of years
How are crude oil and natural gases produced?
formed from deposits of plankton. these fossil fuels form reservoirs under the sea bed when they get trapped in rocks
Explain and describe how the Earth warms up.
1) High energy short-wavelength infrared radiation from the sun passes through the atmosphere and reaches the Earth’s surface. Some of this is absorbed by the Earth
2) Lower energy, long-wavelength infrared radiation is reflected by the Earth’s surface
3) Greenhouse gases in the Earth’s atmosphere absorb the long wavelength radiation that is reflected and re-radiate it in all directions - including back towards the search which increases its temperature.
Name some greenhouse gases
CO2
water vapour
methane
What are examples of human activities that negatively impact the Earth?
Explain how they negatively impact the Earth
- Deforestation = fewer trees = less CO2 removed from the atmosphere via photosynthesis
- Burning fossil fuels = carbon that was locked up in these fuels is released as CO2
- Decomposition of rubbish in a landfill site and increased animal farming = increase levels of methane
How is methane produced?
it is produced by animals during digestion and decomposition of the waste materials
Many scientists believe that the increase in the levels of greenhouse gases in the atmosphere causes global warming and climate change.
Why is this information reliable?
because it has been peer-reviewed
Why do people use simplified models of climate change?
because the Earth’s climate is complex and there are so many variables
What can the impact of climate change include? (7)
- a rise in sea levels: causing devastating floods and more coastal erosion
- more frequent and severe storm events
- changes in the amount and timing of rainfall = areas receiving more rain and others receiving much less
- an increased number of heatwave events,
- more droughts
- changes to the distribution of plants and animals, as some areas warm up enough to become too hot for species to survive
- food shortages in some areas, due to changes in the number of food that countries can produce
What is a carbon footprint?
a measure of the amount of CO2 ns other greenhouse gases released over a full cycle of something
(service, an event, a production)
How can carbon footprint be reduced?
- renewable energy sources or nuclear energy instead of fossil fuels
- wasting less energy by using a more efficient process
- carbon capture and storage (CCS) to prevent CO2 from being released into the atmosphere
- carbon taxes and licenses, to deter companies and individual from choosing options that release lots of greenhouse gases
- carbon off-setting, through activities such as tree planting
- encouraging people to choose carbon-neutral products
What are the problems over reducing carbon footprints?
- disagreements between scientists over the causes and consequences of global climate change
- lack of information and knowledge in the general population
- the reluctance of people to make lifestyle changes
- economic considerations, such as the high cost of producing electricity from alternative energy resources, rather than using cheaper fossil fuels
- disagreements between countries as to what should be done
What’s the word formula for the combustion of methane?
methane + oxygen = water + carbon dioxide
Describe how oxides of nitrogen are produced when petrol is burned in car engines.
Nitrogen from the atmosphere reacts with oxygen from the atmosphere at high temperatures in the engine
What is the main source of atmospheric pollutants
combustion of fuels
What do most fuels, including coal, contain?
carbon
and/or hydrogen
may also contain some sulfur.
What substances are released when fuels undergo combustion?
7
carbon dioxide water vapour, carbon monoxide, sulfur dioxide oxides of nitrogen.
Solid particles and unburned hydrocarbons may also be released that form particulate in the atmosphere.
What environmental and human problems do sulfur dioxide and oxide of nitrogen cause?
Acid rain
respiratory problems
What problems do carbon particulates cause?
Global dimming and health problems for humans
What problems do carbon monoxide cause?
toxic gas = detrimental to health
acid rain
What is a catalytic converter?
what does it do, what gases does it change
it converts toxic gases from the exhaust pipe to harmless ones - this is in the exhaust systems
They contain platinum and rhodium, which act as catalysts
it changes carbon monoxide into carbon dioxide.
Changes oxides of nitrogen to nitrogen
What enables the catalytic convertors to be good at their job?
A honeycomb structure is coated in platinum and rhodium.
The honeycomb structure increases the surface area to volume ratio, increasing the rate at which the harmful gases carbon monoxide, nitrous oxide and methane are converted into carbon dioxide, nitrogen and water.
since the metals used are catalysts, they lower the activation energy also increases the rate of reaction.
