Chemistry Of The Atmosphere Freesciencelessons Flashcards
What percentage of each gas are in the earths atmosphere?
78% nitrogen,21% oxygen and small proportions of other gases (e.g. carbon dioxide,water vapour and nobles gases such as argon)
How old is the earth?
Around 4.6 million years old
What do scientists believe about what happened in the first billion years?
Intense volcanic activity releasing gases
How did the oceans form?
As the earth cooled, water vapour condensed forming oceans
Why was there more CO2 than O2 in the earths early atmosphere?
Volcanoes released huge amounts of CO2
What planets was the earths early atmosphere compared to?
Mars and Venus
What else did volcanoes release?
Methane and ammonia
How did precipitates and sediments form?
Some of the CO2 dissolved into the oceans forming a weak acid which reacted with the water forming precipitates then sediments of carbonate rock
How did shells and mussels decrease CO2 levels?
Some CO2 was used in corals and shells and when mussels died they formed sedimentary rock which removed CO2 from the atmosphere
Why did oxygen levels rise?
Photosynthetic algae evolved in oceans and produced oxygen so more plants evolved and amount of O2 continued to rise until animals too could evolve
How did fossil fuels reduce the CO2 levels?
They trapped carbon inside causing CO2 levels to fall
What are the 3 fossil fuels?
Coal,oil,gas
Are fossil fuels renewable or non-renewable?
Non-renewable
How is coal formed?
From the remains of ferns and trees as they were covered in sediment and compressed (high temperature and pressure)
How is crude oil formed?
From plankton - tiny plants and animals found in the sea
How does natural gas form?
From the hydrocarbon methane and is found near oil deposits as they are both formed from plankton
What do all fossil fuels contain?
Trapped carbon
