Chemistry of the atmosphere Flashcards
What gases are in the atmosphere today?
Nitrogen 78%
oxygen 21%
small proportion of co2 and water vapour and noble gases
stayed constant for about 200 million years
How old is the earth atmosphere?
4600 million years old
What did the intense volcanic activity release ?
WATER VAPOUR- as the earth cooled the water vapour condensed to form the ocean
CARBON DIOXIDE-mainly co2 and not o2 it was like the atmosphere of Venus and Mars today
What small quantities of gases were released by intense volcanic activity?
NITROGEN gradually-build up the atmosphere
METHANE & AMMONIA-small proportions
What i the difference between the atmosphere today and the early atmosphere?
TODAY-Small amount of co2,21% of o2
EARLY-large amount of co2 contains small amount of o2
How did co2 decrease during the early atmosphere?
1)water vapor condensed to form ocean
some of co2 dissolved in the water to form a weak acid
2)reacted with minerals in the sea to form precipitate
What happened once the sea formed a precipitate?
3)overtime this formed sediment of carbonated rock on the sea bed
some of the co2 was used to make corals and shells
What happened once the shells died?
4)when they died they formed sedimentary rock limestone
this removed co2 from the atmosphere
How did oxygen enter the atmosphere?
1) Photosynthetic algae evolved in the ocean
2) Photosynthesis produced oxygen and entered the atmosphere
How did photosynthesis make co2 levels fall?
it takes in co2
and then can be trapped into fossil fuels
How did o2 levels increase?
3) Over the years plants evolved which increased the amount of o2
4) At some point the level of o2 reached the point where animals could evolve
What remains are used for coal?
formed from the remains of fern and trees
How is gas formed?
mainly hydrocarbon methane
formed from plankton similar to formation of oil
Hoe is oil formed?
formed from plankton which are found in the sea they die and settle in a sea bed and if o2 is not present they do not decompose and compressed by sediment
heat and pressure turn it into oil
What prevents bacteria from carrying out decomposition in the formation of coal?
if die in marshy wetlands then they do not decompose due to lack of o2 or acidic conditions
these both prevent bacteria from carrying out decomposition
