Topic 9 - Chemistry of the Atmosphere Flashcards
How was the early atmosphere formed?
The surface of the earth was covered in volcanoes that erupted to release lots of gases.
What gases made up the early atmosphere?
Mostly carbon dioxide, virtually no oxygen. Volcanic activity also released some nitrogen (which built up over time), water vapour and small amounts of methane an ammonia.
What planets can the early atmosphere of earth be compared to?
Mars and Venus.
How were oceans formed?
When water vapour in the atmosphere condensed.
How was lots of carbon dioxide removed from the early atmosphere?
It dissolved in oceans.
What happened to the dissolved carbon dioxide?
It went through a series of reactions to form carbonate precipitates that formed sediments on the seabed.
How were green plants and algae able to evolve?
They absorbed some of the carbon dioxide so they could photosynthesise.
How did marine animals evolve?
Their shells and skeletons contains carbonates from the oceans.
What happened to some of the carbon the organisms took in from the atmosphere and oceans?
It became locked in rocks and fossil fuels after the organisms died.
Describe how organisms reduce carbon dioxide levels in the atmosphere.
When plants, plankton and marine animals die, they fall to the seabed and get buried by layers of sediment. Over millions of years, they become compressed and form sedimentary rocks, oil and gas - trapping the carbon within them and helping to keep carbon dioxide levels in the atmosphere reduced.
How are crude oil and natural gas made?
Formed from deposits of plankton. These fossil fuels form resevoirs under the seabed when they get trapped in rocks.
What is coal?
A sedimentary rock made from thick plant deposits.
What is limestone?
A sedimetary rock, mostly made of calcium carbonate deposits from the shells and skeletons of marine organisms.
What is the equation for photosynthesis?
carbon dioxide + water = glucose + oxygen.
When did algae first evolve, when did green plants evolve?
2.7 billion years ago. Over the next billion years green plants also evolved.
What did oxygen levels building up result in?
More complex life like animals could evolve.
When did the atmosphere reach a composition similar to how it is today?
About 200 million years ago.
What is the appoximate composition of the atmosphere today?
80% nitrogen, 20% oxygen and small amounts of carbon dioxide, noble gases and water vapour.
What are examples of greenhouse gases?
Carbon dioxide, methane and water vapour.
What do greenhouse gases act like?
An insulating layer in the Earth’s atmosphere, allowing the Earth to be warm enough to support life.
What is the greenhouse effect?
Short wavelength radiation hits the earth by the sun, this is then reflected back off the Earth as long wavelength radiation which is absorbed by greenhouse gases. They then re-radiate it in all directions including back towards the earth. The longwave radiation is themal radiation, so it results in warming the surface of the earth.
What forms of human activity affect the amount of greenhouse gases in the atmosphere?
- Deforestation - fewer trees means that less CO2 is removed from the atmosphere via photosynthesis.
- Burning fossil fuels - carbon that was ‘locked up’ in these fuels is released as CO2.
- Agriculture - more farm animals produce more methane through their digestive processes.
- Creating waste - more landfill sites and more waste from agriculture means more CO2 and methane released by decomposition of waste.
What can extra carbon dioxide from human activity lead to?
Climate change - the average temperature of the earths surface has been increasing.
How do you know whether the information about climate change from scientists is reliable?
It has been peer reviewed.
