Fuels and Energy from Fuels

Question 1

define a fossil fuel

Answer 1

natural fuel that is formed in the earth from plant or animal remains

Question 2

what is Coal

Answer 2

combustible fossil fuel formed by the partial decay of plant matter

Question 3

what are non-renewable (!) resources

Answer 3

resources that cannot be replenished as quickly as it is being consumed

Question 4

what is a fuel (!)

Answer 4

a substance that burns in air or oxygen to release a usable amount of energy

Question 5

list types of bio fuels

Answer 5

biogas, bioethanol, biodiesel

Question 6

list types of fossil fuels

Answer 6

methane, octane, CSG(coal seam gas), LPG(liquid petroleum gas, diesel/petrodiesel

Question 7

Why are many fuels measured by mass or volume instead of by moles?

Answer 7

This is because many fuels are a mixture of different compounds and fuels and hence the exact molar mass is not known

Question 8

fuels have … (low or high) boiling point, flashpoint, flammability

Answer 8

low boiling point, low flashpoint, high flammability

Question 9

outline two safety measures for fuels

Answer 9

1) keep away from naked flames(flammable)

2)keep in a well ventilated area(asphyxiation/suffocation)

Question 10

what to focus on when discussing properties of fuels

Answer 10

the size of the molecule

the type of intermolecular bonds which form

Question 11

describe hydrogen bonds

Answer 11

bonds forming between a hydrogen atom which is covalently bonded to a NOF, and a NOF on another molecule

Question 12

when is the flashpoint of a fuel a safety hazard

Answer 12

If the flashpoint is below room temperature since a spark could cause immediate ignition

Question 13

what is a flammable liquid

Answer 13

any liquid with a flashpoint below 37.8 C

Question 14

what is a combustible liquid

Answer 14

a liquid with a flashpoint greater than 37.8 C

Question 15

how does a liquid burn

Answer 15

the vapour is burned not the liquid itself. As temperature increases more vapour is produced which ignites

Question 16

renewable fuel

Answer 16

can be replenished at a rate similar to which they are being used

Question 17

list some renewable energy sources

Answer 17

any Biofuel, geothermal energy, solar energy, hydro-electricity

Question 18

list some non-renewable energy sources

Answer 18

any fossil fuels, nuclear energy sources

Question 19

why are biofuels renewable + carbon neutral

Answer 19

-Made from plant matter(biomass) so renewable.
-Carbon neutral because plants undergo photosynthesis and absorb CO2 from the atmosphere and hence when they die and are converted from plant matter to fuel
-This CO2 is released back into the atmosphere via combustion which means that there is no net release of CO2.
(However may not be exactly net zero due to transportation of fuel)

Question 20

what are biofuels

Answer 20

fuel sourced from organic matter

Question 21

what is biogas

Answer 21

gaseous fuel produced by the anaerobic breakdown of organic matter

Question 22

what is bioethanol

Answer 22

fuel produced from the fermentation of glucose in organic matter using yeast

Question 23

what is biodiesel

Answer 23

fuel produced by the esterification of fats oils in organic matter

Question 24

what is fermentation

Answer 24

breakdown of a substance in presence of microorganisms such as yeast

Question 25

what is transesterification

Answer 25

reaction that produces biodiesel

Question 26

what is biogas made of

Answer 26

mixture of gases and approx. 60% methane

Question 27

Outline two ways to produce biogas

Answer 27

1-place a funnel over plant materials eg algae ,wood, or compostable garbage and collect methane and CO2 via a pipe (to a tank)
2-Digester which uses same principle but is a more efficient and controlled apparatus/process

Question 28

equation for fermentation of glucose

Answer 28

glucose –> 2ethanol + 2CO2

Question 29

equation for biodiesel production

Answer 29

triglyceride + 3methanol —> biodiesel + glycerol

Question 30

what does a molecule need to have to form biodiesel

Answer 30

-acid group
-long hydrocarbon chain

Question 31

biodiesel AKA

Answer 31

methyl ester

Question 32

main functional group of biodiesel

Answer 32

ester

Question 33

4 comparisons between biodiesel and petrodiesel

Answer 33

-biodiesel has a higher viscosity (harder to flow through lines) whereas petrodiesel has lower viscosity
-Biodiesel is more hygroscopic than petrodiesel (absorbs water)
-biodiesel produces less energy per gram
-biodiesel has a higher melting point

Question 34

Briefly outline 4 advantages of biodiesel

Answer 34

-lower net CO2 emissions (when plant matter used) as the CO2 released is partially offset
-no sulphur emissions
-unburnt hydrocarbons eg. benzene rings are almost eliminated
-more complete combustion due to C=O (easier to oxidise)

Question 35

Briefly outline 6 disadvantages of biodiesel

Answer 35

-hygroscopic hence water can be suspended into biodiesel (decreasing energy content)
-forms gel/crystalises at higher temperatures leading to poor flow at low temperature
-high colourpoint hence poor flow and combustion at lower temperatures
-more likely to oxidise due to the ester link which can form gemlike substance and block fuel lines
-lower energy content due to C=O which increases likelihood of oxidation and increases dipole dipole interactions
-land clearing and water needed to grow crops to produce bioethanol