Chemistry of the atmosphere Flashcards
Describe how the oxygen levels in the early atmosphere increased?
- Algae produced oxygen by photosynthesis 2.7 billion years ago.
- Over the next billion years, plants evolved and produced oxygen by photosynthesis.
Write a word and balanced symbol equation for photosynthesis.
As well as increasing oxygen levels, what other effect did algae and plants have on the atmosphere?
Reduced carbon dioxide in the atmosphere (by photosynthesising)
One theory suggests that the Earth’s early atmosphere was shaped by intense volcanic activity. What was the main gas present in the atmosphere at this time?
Carbon dioxide
What are the issues with the way in which the media portrays global climate change?
The media portrays simplified models, speculation and opinions which may lead to bias.
How did the amount of carbon dioxide in the early atmosphere reduce?
- Dissolved in the oceans
- Locked up in sedimentary rocks (carbonate precipitate forming sediment)
- Locked up in fossil fuels (calcium carbonate shells of marine organisms)
What are the approximate proportions of nitrogen and oxygen in our atmosphere (as a fraction and percentage)?
- Nitrogen (4/5 or 80%)
- Oxygen (1/5 or 20%)
What type of combustion often results in carbon monoxide and soot (carbon particles) being released?
Incomplete combustion
Explain what is meant by the ‘Greenhouse Effect’.
- The Greenhouse Effect is the warming of the Earth’s surface due to greenhouse gases.
- The greenhouse gases don’t absorb the short wave radiation from the sun
- However, they do absorb the long wavelength radiation that is reflected off the Earth’s surface.
- They then re-radiate this long-wavelength radiation, some of which travels back towards Earth - giving a warming effect.
Why is there only limited evidence of what the early atmosphere was like and how it evolved?
Because there is such a large timescale (4.6 billion years).
Do most scientists agree that human activities are causing global climate change?
Yes, evidence for climate change has been peer- reviewed and most scientists believe human activities will cause the Earth’s temperature at the surface to rise.
Describe how coal is formed.
- Plant deposits fall to the bottom of the sea.
- The plant deposits are covered by layers of sediment.
- Over millions of years, the plant deposits are compressed and coal is formed.
Describe how crude oil is formed.
- Deposits of dead plankton collect at the bottom of the sea.
- They become buried by layers of sediment and are compressed over millions of years.
- Crude oil and natural gas are then formed and are found as resevoirs deep underground.
Name the two gases that cause acid rain.
- Sulfur dioxide
- Oxides of Nitrogen
For approximately how many years have the proportion of gases in the atmosphere stayed the same?
200 million years