Chemistry Of The Atmosphere Flashcards
How long ago did the earth form?
4.6 Billion years ago
4 billion years ago there was intense volcanic activity, what did they release?
●Mainly CO2
●Water vapour (condenses to form oceans)
●Small proportions of other gases like ammonia and methane
●Nitrogen (gradually built up in the atmosphere)
What happened to the gases in the atmosphere between 4 billion years ago and 2 billion years ago?
●Decrease in CO2 and other gases
●Increase in oxygen and nitrogen
What happened between 2 billion years ago and now?
●Decrease in CO2
●Increase in nitrogen and oxygen
What things happened which shaped the atmosphere between 3 billion to 1 billion years ago?
Green plants and algae evolve and:
●CO2 reduced as plants take in and give out oxygen
●Microorganisms that can’t tolerate oxygen are killed off
●Carbon from CO2 becomes trapped in sedimentary rocks formed from the shells + skeletons of marine organisms
●Other gases react with oxygen to release nitrogen
●Nitrogen produced by bacteria removing nitrates from decaying plant material
What is the atmosphere like now?
●Now about 20% oxygen and 80% nitrogen in the atmosphere
●Amount of carbon dioxide has greatly decreased
When did algae start producing oxygen?
2.7 billion years ago
What is the symbol equation for photosynthesis?
6CO2 + 6H20 —–> C6H12O6 + 6O2
What caused animals to evolve?
When plants evolved and the amount of oxygen in the atmosphere rose, eventually there was enough oxygen for animals to evolve
Why was there an increase of oxygen levels?
●Algae and plants photosynthesise, CO2 and water reacts to produce glucose and oxygen
●Algae behan producing oxygen 2.7 billion years ago
●After plants evolved, amount of oxygen in atmosphere rose
●Eventually there was enough oxygen in the atmosphere ti allow animals to evolve
Why has there been a decrease of carbon dioxide levels?
●As plants and algae evolve, decrease of CO2 as plants use it up when photosynthesise
●Due to CO2 getting locked up in sedimentary rocks (limestone) and fossil fuels (coal, crude oil)
●Reduced due to reaction between CO2 and sea water
What does the reaction between carbon dioxide and sea water produce? (Decrease of CO2 in air)
●Insoluble carbonates deposited as sediments
●Soluble hydrogen carbonates
But too much CO2 dissolving in oceans can harm marine life
The reaction between CO2 and sea water can be bad, but why?
Too much CO2 dissolving in oceans can harm marine life, such as coral reefs
What is limestone and how is it formed?
Limestone contains calcium carbonate and can be formed from the shells and skeletons of sea creatures
What is coal?
A sedimentary rock formed from plant deposits that were buried and compressed over millions of years
What atmosphere of 2 planets are thought to be like the earth’s early atmosphere?
Venus and Mars
Why are greenhouse gases increase temp of earth?
Greenhouse gases absorb outgoing infrared radiation which increases temp
Name 3 green house gases?
Methane, water vapour, carbon dioxide
What would happen if there was no greenhouse gases?
Earth would be too cold to support human life
What would happen to water if there was no greenhouse gases?
Water would be a solid as earth would be very cold
How do burning fossils fuels increase CO2 levels?
Fossil fuels containing locked up carbon,burning the fuels releases carbon dioxide (as carbon combines with oxygen in air)
How does deforestation lead to increased CO2 levels?
There are fewer trees taking in CO2 for photosynthesis
