Fuels - heinmann Flashcards
define fuels
A fuel is a substance with stored energy that can be released relatively easily for
use as heat or power
non renewable resources…
are those that are used faster than they can be replaced
where did organic matter in fossil fuels get its energy and what can this energy considered to be
organic matter retains some of the energy that plants first accumulated by photosynthesis. chem energy can be considered to be trapped solar energy
3 examples of non renewable fuels
coal, oil and natural gas
how are fossil fuels made
from organic matter buried under tonnes of mud, sand and rock; undergoing complex chemical changes
wood is ___ percent carbon
50
what happens as wood turns into coal
carbon content increases
proportion of hydrogen and oxygen decreases
what does coal contain
coal is a mixture of large molecules of carbon hydrogen, nitrogen, sulfur and other elements
what effect does the water in coal have when it is burnt
the energy released causes the water to evaporate, reducing the amount of net heat released
amount of water in coal ____ as it changes from wood to coal
decreases
why is black coal a better source of fuel compared to peat
contains the least water and therefore the highest
percentage of carbon
peat is ___ percent carbon and releases ___ of heat
60 25 kj/g
brown coal is ___ percent carbon and releases ___ of heat
70 30kj/g
black coal is ___ percent carbon and releases ___ of heat
90 35 kj/g
crude oil is a mixture of
hydrocarbon molecules that are mostly
members of the homologous series of alkanes
alkanes are
hydrocarbons with
the general formula Cn
H2n+2.
Alkanes are commonly found in crude oil
how is crude oil made useful
by fractional distillation, bcz crude oil isnt useful but contains useful compounds.
fraction is still a
mixture of hydrocarbon compounds.
it doesnt produce pure substances.
fractions can be used as fuels, or treated
further to produce more specific products through chemical processes.
components of natural gas
mostly methane. small amounts of ethane and propane. may also have water, sulfur, nitrogen and co2
where can natural gas be found
- gas reservoirs - trapped between layers of rock
- component of petroleum deposits
- as CSG - coal seam gas - in coal deposits
- as shale gas - trapped in shale rock
what is the chem equation for photosynthesis
6CO2(g) + 6H2O(l) → C6H12O6(aq) + 6O2(g)
what are biofuels
renewable fuels derived from plant materials such as
grains (maize, wheat, barley) sugar cane, vegetable waste, and vegetable oils.
what are the 3 main types of biofuels
biogas, bioethanol and biodiesel
how is bioethanol produced
what is the reaction
enzymes catalyse the breakdown of starch in grain crops to glucose. other yeast enzymes convert the glucose and other small molecules into ethanol and co2 in the fermentation reaction:
C6H12O6(aq) → 2CH3CH2OH(aq) + 2CO2(g).
it is then distilled to remove the water to form pure bioethanol
what are biofuels
gas produced from organic waste by anaerobic bacteria
how are biofuels produced
break down of complex carbs and proteins into simple c02 and methane by anaerobic bacteria in a digester.
rotting rubbish and waste is used.
what are the main components of biofuel
methane and co2
what are biodiesels
mixtures of organic compounds called esters made by chem reactions between animal fats or vege oils and alcohol, most commonly methanol CH3OH.
for oils usually soyabean, canola or palm oil are used.
give examples of renewable fuel sources
bioethanol, biodiesel, biogas
give examples of non renewable fuel sources
coal,
oil, LPG, natural gas, coal seam gas
why is it necessary to use fractional distillation to treat crude oil
Crude oil consists of a range of hydrocarbons with different
boiling temperatures. Fractional distillation is needed to separate
them.
1.2 Fossil
what kind of reaction occurs to form biodiesel
Transesterification reaction between the triglycerides (fats) and alcohol usually methane
what 3 factors are crucial to ensure biofuels are sustainable
food vs fuel - production of biofuels shouldn’t reduce amount of food available. feedstock for biofuels should be waste materials or non edible plant material
land requirements - need 100M hectares to grow enough biofuels
energy input vs energy output - The total amount of energy required to grow, collect, and convert the feedstock into a
usable biofuel should only represent a small percentage of the total energy available
from combustion of the biofuel.
how is coal formed
by decaying organic matter in sediments over millions of years
how is natural gas formed
by decomposition of plants and animals over millions of years
why is it so difficult to make a carbon neutral bio fuel
Seeds need to be bought, transported, and planted using machinery that would normally use non-renewables.
which fuel is a mixture of methyl esters
biodiesel
what is the bi product of a traserstification reaction
glycerol
