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Chemistry 2: Chemistry of the Atmosphere (Earths Early Atmosphere: (What…
Chemistry 2: Chemistry of the Atmosphere
Earths Early Atmosphere:
What caused the early atmosphere:
Volcanic Eruptions - Main gas = Co2
Oceans formed:
Eruptions released water vapour that condensed
Earth is 4.6 Billion years old
Mars & Venus have a similar atmosphere:
How many years has the atmosphere been the same?
200 Million Years
Other Gases produced by Volcanos:
Nitrogen & small amounts of Methane and Ammonia
Greenhouse Gases:
Greenhouse gases Maintain temps high enough for life
Greenhouse Effect:
Gases are like an insulating layer
They don't absorb Short wavelengths (From Sun)
They absorb long wavelengths (Thermal) from the earth
The gases re-radiate heat in all directions = Warming the earth
3 Greenhouse gases:
CO2
Methane
Water vapour
Human Contributions:
Activities increase Methane:
Waste landfill
Livestock & Rice Farming
Incomplete combustion
Extracting, Handling, Transporting & Refining Fossil fuels
Peer-Reviewed evidence:
Other scientists review results before they are published
Helps detect false claims -- Doesn't mean that findings are correct tho
Activities that increase CO2:
Burning Fossil fuels
Deforestation
-- Trees burnt -> CO2
-- Trees Decay -> CO2
-- Less Trees -> Less CO2 taken from atmosphere
Cement Production (Thermal decomposition of limestone) -> CO2
Oxygen Increased:
What happened next:
Plants evolved & Oxygen gradually increased so animals could evolve
What produced the O2:
Algae & plants via Photosynthesis
When did algae start producing O2:
~ 2.7 Billion years
CO2 Decreasing
& Others Forming:
Limestone Formed:
Marine organisms died & fell to the sea bed
Layers of sediment buried them
Over millions yrs - Got compressed and Limestone rocks Formed
Crude oil (+ Natural gases) Formed:
Plankton dies & Fell to seabed (Partially decomposed)
Covered by mud - Change into rock
Temp/ Pressure caused chemical & Physical changes
What caused the CO2 % to decrease:
Photosynthesis by algae and plants
Dissolved in oceans & Carbonates precipitated (Producing Sediments)
Formation of sedimentary rocks
Marines animals shells/ Skeletons contained carbonates
Fossil fuels
Coal Formed:
Giant plants/ Ferns Died
Formed at bottom of swamps & Sediment built-up
Millions yrs - Of pressure/ Heat = Chemical & Physical changes