8.1-8.3 Flashcards
__% of energy in sunlight reaches earth’s surface and is converted (w/ photosynthesis) to chemical energy (carbohydrates)
0.3%
carbohydrates
(CH2O)n
- 2 hydrogen + 1 oxygen / atom of carbon
photosynthesis equation
CO2 + H2O –> CH2O + O2
products of photosynthesis are..
less stable (by ~ 450 kJ mol-1 carbon) bc of dissociation into atoms
green plants __ amount of carbs for their own energy
~1/2
reverse reaction of photosynthesis
combustion/respiration
- releases energy
respiration
provides aerobic (w/ oxygen) organisms w/ energy needed for functions
anaerobic
w/o oxygen
what makes up fossil fuels?
- decaying plant matter = buried reduced-carbon compound deposits
dead plant matter + ↑ temps + ↑ pressure = coal, oil, gas
- coal = terrestrial
- oil = marine (lignin)
where/how is solar energy stored?
in fossil fuels
if we consume all fossil fuels, will we run out of oxygen?
NO…amount of CO2 released = significant bc of small relative amount in atmosphere
- O2 has large relative amount in atmosphere so release of more has low influence
total amount of recoverable fossil fuel energy
~ 3.7 x 1019 kJ
origin (location) of petroleum and natural gas deposits
marine (oceans)
amount of reduced carbon produced through photosynthesis in oceans/year:
25-50 billion tons/year
- mostly recycled atmospheric carbon
where is petroleum found?
underground reservoirs (where oceans were historically located or where they currently are)
what is petroleum?
crude oil and (refined and unrefined)
by what process is methane, ammonia, and water released from sediments in the ocean?
anaerobic bacteria digest buried biological debris
organic rearrangement reactions
buried sediment + ↑ temps + ↑ pressure =
↓ bacterial action =
releases CH4 (methane) + light hydrocarbon gases
-gases accumulate in pockets under rock
gas hydrates/clathrates
CH4 contained undersea/permafrost
- hydrogen-bonded H2O molecules surround CH4 –> form solid material
- stable @ ↓ temp/↑ pressure)
- found @ 300+ m. depth
what is the largest component of natural gas?
methane
what produces the largest amount of stored methane?
- anaerobic bacteria = trapped @ depth/cold temp in water
- methane deposits = amnt > (coal + oil + gas)
- no practical method for extraction (w/o releasing large amnts of CH4 into atmosphere)
abiotic hydrocarbons produce methane when…
hydrocarbons + ↑ depth + ↑ temp + ↑ pressure = carbonate rock –> (reduced) –> CH4
13/12C isotope
- ↓ in organic compounds (derived from living matter) bc heavier isotope
- reacts slowly (in photosynthesis)
CH4 samples = __ in 13/12C @ increasing depths; what does this mean?
increases
- there is likely an abiotic source (but it’s unknown)
