C1 - Atmosphere Flashcards
How can nitrogen, hydrogen, carbon monoxide and form amino acids?
nitrogen and hydrogen can form ammonia; carbon monoxide and hydrogen can form methane and water; methane, ammonia and water formed amino acids in the Urey-Miller experiment.
Why don’t scientists know for sure how life began?
Because no one was around when the first organisms formed.
What causes the amount of carbon dioxide to increase rapidly?
Increased burning of fossil fuel, deforestation.
What do we mean by ‘locked up carbon’?
Carbon dioxide that was used to form fossil fuels or carbonate rocks.
What causes carbon dioxide to be removed from the atmosphere?
photosynthesis, formation of carbonate rocks and marine shells, dissolving in the oceans, locked up in fossil fuels.
What causes carbon dioxide to be released into the atmosphere?
Respiration, combustion of fossil fuels, warming of oceans releases dissolved carbon dioxide.
Why is the Urey-Miller experiment not fully reliable?
Because they only selected the gases that are needed to produce amino acids. There might not have been any lightening and other gases might have been present.
What is the composition of the atmosphere?
78% Nitrogen, 21% oxygen, 0.03% carbon dioxide, 1% argon
The early atmosphere contained mainly carbon dioxide (95%), methane, ammonia and water vapour. Where did these gases come from?
Volcanic activity
Describe what happened to the gases that made up the early atmosphere (ammonia, methane, carbon dioxide).
Plants absorbed CO2 during photosynthesis. CO2 dissolved in the oceans. Plants released O2 which
reacted with the methane to form more CO2 and H2O. O2 also reacted with ammonia to form N2 and H2O
How did the oceans form?
As the atmosphere cooled, water vapour condensed.
Nitrogen boils at - 196oC, methane at -169oC. If the temperature is -179oC, what is the state of nitrogen and methane?
Nitrogen will be a gas because its boiling point is lower than -179oC , methane a liquid because its boiling point is higher than -179oC.
Describe fractional distillation of air.
Filter air to remove water vapour and dust. Cool air to remove water and carbon dioxide as these would freeze and block the pipes of the fractionating tower. Cool air to - 200oC to liquefy it. Liquid air enters the tower and gradually warmed up. Nitrogen gas boils off first and rises to the top of the tower. Liquid oxygen and argon are left behind and tapped off at the bottom of the tower. To separate the oxygen and argon, a second fractionating column is used.
