The atmosphere and rates of reaction Flashcards
Give the gases and proportions of the earth’s atmosphere?
Nitrogen 78%
Oxygen 21%
other gases (1%) e.g. carbon dioxide water vapour and noble gases e.g. Argon
How long have the gases in the atmosphere stayed constant?
Around 200 million yeas
Why cant scientists be certain about the early earth’s atmosphere
Because the earth is 4600 million years old
What do scientists think happened during the first billion years
They think there was intense volcano activity
What did volcanos release?
Gases which form the atmosphere,
Name one gas released by volcanoes
Water vapour
How were oceans formed?
Water vapour released by the oceans condensed
Name another gas released by volcanoes
Carbon dioxide
Why was the earths atmosphere similar to the atmospheres of mars and Venus?
Because it was made up of mainly carbon dioxide and little or no oxygen
Name even more gases which volcanos produced?
Nitrogen which gradually built up in the atmosphere, and small amounts of methane and ammonia
What did the earths early atmosphere consist of?
mainly carbon dioxide and small but increasing amuotns of nitrogen
Give three differences between the earth’s early atmosphere and the atmosphere of the earth today
The level of nitrogen increased and the early atmosphere contained of large amounts of carbon dioxide and the atmosphere today only contains a little amount, the early atmosphere of the earth contained very little oxygen and the atmosphere of the earth today contains 21% oxygen
How did the level of carbon dioxide in the atmosphere go down?
When oceans were forming some carbon dioxide dissolved in the oceans to form a weak acid, this then reacted with minerals in the sea to form precipitates, over time this formed sediments of carbonate rocks on the sea bed, some of the carbon dioxide in the sea was used to make corals and shells of organisms such as mussels, when these organisms died they formed sedimentary rock limestone, plants evolved which take in carbon dioxide for photosynthesis, the carbon can then be trapped in fossil fuels causing level of carbon dioxide to fall
Where did the oxygen come from that we see today?
Around 2.7 billion years ago photosynthetic algae first evolved in the oceans, photosynthesis produced oxygen which entered the atmosphere, over the following billion years plants evolved, increasing the amount of oxygen in the atmosphere, at a certain point the level of oxygen reached to the point where animals could evolve
Give the chemical symbol and word equation for photosynthesis
carbon dioxide plus water over light gives glucose plus oxygen
.6CO2 + 6H20 gives C6H12O6 +602
How many years does it take for fossil fuels to form?
Millions of years
Are fossil fuels renewable or non-renewable?
Non-renewable
How is coal formed?
From the remains of ferns and trees, if these die in marshy wetlands then they do not decompose, this can be due to lack of oxygen or acidic conditions, over time the plant remains are covered with sediment and compressed, high temperature and pressure creates coal
What prevents bacteria from decomposing
lack of oxygen or acidic conditions don’t allow the decomposition in bacteria
How is crude oil formed?
From plankton which are tiny plants found in the sea, when these die they settle in mud in the sea bed, if oxygen is not present they do not compose, over time they are compressed by sediment, heat and pressure then convert them into crude oil
What is natural gas mainly?
Mainly the hydrocarbon methane
Where do we find natural gas?
Near deposits of oil
How is natural gas formed?
Form plankton in a similar way to crude oil
What do all fossil fuels contain?
Carbon, this is part of the carbon dioxide taken in by photosynthesis