Chemistry of the Atmosphere Flashcards
What are the percentages of gases in the air?
Oxygen - 21%
Nitrogen - 78%
CO2 - 0.04%
Argon - 0.9%
How can scientists measure historic atmospheric composition?
Analysing tiny air bubbles trapped in ICE CORES in the poles
The air bubbles were trapped as the snow and ice was laid down tens of thousands of years ago and provide a snapshot of what our atmosphere was like back then
What was Earth’s early atmosphere like?
Earth used to be molten for millions of years, where there was NO ATMOSPHERE
When the molten materials solidified, volcanoes were formed which released gases from Earth’s interior.
Gravity prevented these gases from escaping forming an ATMOSPHERE
There was mostly CO2 and water vapour present, and little or no oxygen present
When the earth cooled the water vapour condensed and formed OCEANS
CO2 is a water soluble gas, so dissolved in the oceans which reduced the levels of CO2 in the atmosphere
How were oxygen levels increased in the atmosphere?
Primitive plants and algae begun PHOTOSYNTHESISING which used up CO2 from the atmosphere and released OXYGEN
Over long periods of time the oxygen increase and the CO2 decreased
Marine algae are thought to be responsible for about 90% of all the atmospheric oxygen produced
What happens when shortwave light radiation from the sun hits the earth?
It hits the Earth’s surface and energy is absorbed then re-emitted from the surface as INFRARED RADIATION (heat)
What do greenhouse gases do?
They can ABSORB and STORE the infrared radiation which is emitted from the surface of the Earth which can result in the Earth becoming hotter
What are some examples of greenhouse gases?
CO2, Methane and water vapour
What is the enhanced greenhouse effect?
Where increasing levels of gases such as CO2 or Methane cause significant upset in the Earth’s natural conditions by trapping extra heat energy
How can carbon dioxide be exposed to the atmosphere?
Combustion of wood and fossil fuels, respiration of plants and animals and thermal decomposition of carbonate rocks
How can methane be exposed to the atmosphere?
Digestive processes of animals, decomposition of vegetation and bacterial action in swamps and rice fields
How do we match the increasing energy demands of the growing human popualtion?
Burning fossil fuels as a cheap and reliable energy source and more landfill sites to dispose of waste which increases emissions of methane by decomposition
How does deforestation affect the climate?
Trees remove CO2 from the atmosphere during photosynthesis, so by mass removal of large forests, the amounts of atmospheric CO2 increases as a result
How can we estimate past climate conditions?
Analysis of fossil records, tree rings, gas bubbles trapped in ice, etc
However none of these methods provide as accurate data as we have today, and they do not represent data on a global scale
What are some effects of climate change?
Rising sea levels, frequent and intense droughts, storms, infrequent weather, extreme heat waves and rainfall, etc
What causes rising sea levels?
Melting of polar ice caps and glaciers due to warming global temperatures.
What are the effects of rising sea levels?
Erosion of coastal regions, habitat destruction for bids, fish and plants
Low lying cities are likely to see flooding and permanent loss of usable land
What are some effects of droughts?
Crop failure, collapse of agricultural production and starvation
What is the life cycle assessment?
A technique used to assess the environmental impact associated with all the stages throughout the life cycle of a product, service or event
It takes into account raw extraction of the materials, how it is manufactured, how it is distributed and how it is disposed of at the end of its life
It is a very difficult process because there are so many factors to consider, such as the emissions released in sourcing all of the parts of a computer!
How can we quantify emissions of CO2?
In terms of a CARBON FOOTPRINT
What is a carbon footprint?
The amount of carbon dioxide generated by a persons’ activities
How can we reduce our carbon footprint?
- Using renewable energy supplies (eg. solar or wind energy instead of burning fossil fuels)
- Governments and global organisations are slowly switching to greener and more sustainable sources of energy
- Cutting unnecessary journeys
- Using public transport
- Reducing consumption of meat
- Recycling
- Electric vehicles
What are the challenges with reducing our carbon footprint?
- Governments tend to be slow to act on these issues as they fear a negative impact on their economy
- Difficult to convince people to change their ways
- Too expensive and too much luxury to sacrifice
What are fossil fuels?
Coal, oil, natural gas, etc
How are some fossil fuels obtained?
Some non-renewable fossil fuels are obtained from crude oil by fractional distillation
What is carbon monoxide?
An extremely poisonous gas which combines with haemoglobin in blood and prevents it from carrying oxygen, reducing oxygen supply to brain which can cause fainting, coma or death
Colourless, odourless, difficult to detect
What is soot?
Clumping together of carbon particles released from incomplete combustion form SOOT
Causes respiratory problems and accelerates corrosion on infrastructure
What is sulphur dioxide?
Colourless, pungent smelling gas responsible for acid rain, which can cause corrosion to metal and damages aquatic organisms, pollutes crops and water supplies and irritates lungs, throat and eyes
What are oxides of nitrogen?
Come largely from vehicle exhausts and also contribute to acid rain
They produce a photochemical smog and breathing difficulties, in particular for asthma sufferers
How did the earth atmosphere change over time?
- water vapour condensed and formed the oceans (reduced h2o in atmosphere)
- co2 dissolved into oceans (reduced co2)
- dissolved co2 formed carbonates
