Chapter 13 - Chemistry Flashcards
What was the earth’s early atmosphere formed by?
Volcanic activity
What does the earth’s early atmosphere consist of?
It mainly consists of carbon dioxide. There may have nitrogen and water vapour, together with traces of methane and ammonia.
What happens as plants spread over the earth?
The levels of oxygen in the atmosphere increases
What are the thing(s) that decreased carbon dioxide in the early atmosphere?
Photosynthesis by plants and algae, the formation of sedimentary rocks and fossil fuels that contain carbon.
What was any ammonia and methane in the atmosphere removed by?
It was removed by reactions with oxygen, once oxygen has been formed by photosynthesis.
What type of things are in the atmosphere today, and how much of them is there?
Four fifths (about 80%) is nitrogen, and about one fifths (about 20%) is oxygen.
What other gases are there? (Small proportions)
Carbon dioxide, water vapour and noble gases.
Why has the amount of carbon dioxide in the Earth’s atmosphere risen in recent parts?
Due to the amount of fossil fuels being burnt.
What is the earth heated by?
The sun
How much of the sun’s energy is reflected back into space?
30%
What does reducing greenhouse gases in the atmosphere rely on?
Reducing the use of fossil fuels, mainly by using alternative sources of energy and conserving energy
What are the economies of the developed countries based on?
Energy obtained from fossil fuels, so changes will cost money to implement.
What happens when hydrocarbon fuels are burnt in plenty of air?
The carbon and hydrogen in the fuel are completely oxidised. They produce carbon dioxide (the main greenhouse gas) and water.
What can changing the conditions in which hydrocarbon fuels are burnt do?
It can change the products made.
What is formed in insufficient oxygen?
Poisonous carbon monoxide gas is formed.
