fuels

Question 1

catalysts for esterification

Answer 1

KOH
NaOH

Question 2

transesterification

Answer 2

chemical reaction where one ester is turned into another

Question 3

transesterification

Answer 3

chemical reaction where one ester is turned into another

Question 4

transesterification products

Answer 4

ester + glycerol

Question 5

for fuels with a mixture of hydrocarbons, why can’t the heat content be expressed in kJ/mol

Answer 5

bc mixture of hydrocarbons, the molar mass of the fuel is unknown tf mol thus kj/mol cannot be determined

Question 6

for fuels with a mixture of hydrocarbons, why can’t the heat content be expressed in kJ/mol

Answer 6

bc mixture of hydrocarbons, the molar mass of the fuel is unknown tf mol thus kj/mol cannot be determined

Question 7

why must the water produced in the production of biodiesel be removed?

Answer 7

it will make the fuel less efficient

Question 8

why is ethanol miscible in both water and petrol

Answer 8

bc polar hydroxyl group (-OH) can form hydrogen bonds with water
bc non-polar -CH2CH3 form attraction to petrol through dispersion forces

Question 9

what type of molecule is biodiesel made of

Answer 9

long chain hydrocarbons (C8-C20)

Question 10

why is
petrodiesel’s boiling point higher than ethanol’s

Answer 10

While H bonds bw ethanol’s molecules due to polar hydroxyl group is stronger vs dispersion forces, the length of chain and overall intermolecular dispersion forces bw petrodiesel are greater vs H bonds

Question 11

why is methane from biogas less environmentally damaging vs leaving animal waste to decompose in fields

Answer 11

animal waste breakdown releases methane.
Collecting this animal waste and converting the methane released into biogas used for combustion reduces the release of methane. Althogh the combustion of biogas does release CO2 into the atmosphere, the impact this is on the environment is less than methane’s impact on the atmosphere.

Question 12

why is methane considered a non-renewable source

Answer 12

bc methane can be sourced from fossil fuels formed from animal and plant material decomposing over millions of years thus cannot be replenished at the rate of consumption

Question 13

how can methane be classified as a renewable resource

Answer 13

if it is sourced from resources that can regenerate quicker then the rate of consumption eg methanogenic microbes or plant waste

Question 14

advantages of fuel cells vs combustion engine

Answer 14

• less intermediary steps tf more efficient energy conversion
• fuel cells are quieter
• fuel cells produce less total greenhouse gases
  (- sometimes fuel in fuel cell has higher energy content than fuel in engine)

Question 15

disadvantages of fuel cells vs combustion engine

Answer 15

• expensive to set up
  if using hydrogen:
• difficult to access and store hydrogen
• risk leaking H2 reacting explosively

Question 16

what is a fuel

Answer 16

a substance that burns oxygen to release a usable amount of energy

Question 17

safety implications for fuels

Answer 17

• fuels = low BP, FP and high flammability
• thus, they can easily combust and release large amounts of energy
• tf must be stored away from naked flames and be used in well ventilated areas (avoid suffocation)

Question 18

when explaining differences in properties of fuels, focus on….

Answer 18

• size of molecules
• type of intermolecular bonds

Question 19

flashpoint

Answer 19

the minimum temperature at which a particular organic compound gives off sufficient vapour to ignite in air

Question 20

renewable fuels def

Answer 20

can be replensihed at a rate similar to which they are being consumed
- plants can be grown in a relatively short space of time tf converted into desired product for use in fuel

Question 21

examples of renewable energy sources

Answer 21

• solar energy
• hydro-electricity
• wind turbine energy
• biofuels

Question 22

non-renewable energy sources

Answer 22

• fossil fuels
• nuclear energy sources

Question 23

energy transformations in a gas-fired powerplant with turbine

Answer 23

chemical -> thermal -> kinetic (steam) -> kinetic (turbine) -> electrocal

Question 24

how are coal fired plants different from gas fired plants

Answer 24

coal contains carbon and sulfur -> dangerous w/a gas plants produce less pollution and lower sulfur levels

Question 25

biofuel

Answer 25

fuel sourced from organic matter

Question 26

biogas

Answer 26

gaseous fuel produced by the anaerobic breakdown of organic matter by bacteria

Question 27

bioethanol

Answer 27

fuel produced by the fermentation of glucose in organic matter by yeast

Question 28

pros of bioethanol

Answer 28

• renewable resource
• can be made from waste
• CO2 absorbed during photosynthesis offsets CO2 released during combustion
• fewer particulates produced than petrol

Question 29

cons of bioethanol

Answer 29

• limited supply of raw materials from which to produce it
• lower energy content than petrol
• may require use of farmland otherwise used for food production

Question 30

biodiesel

Answer 30

fuel produced by the esterification of fats and oils orginating from animal products or crops

otherwise known as methyl ester

Question 31

reaction to form biodiesel

(w trigylceride)

Answer 31

alcohol + triglyceride -(KOH)-> biodiesel + glycerol

transesterification reaction

more ideal than from FA bc FA produces water which must be removed to enable biodiesel to be a fuel

Question 32

pros of coal

Answer 32

• large reserves
• relatively high energy content
  .

Question 33

cons of coal

Answer 33

• non-renewable
• high levels of CO2 emissions
• less easily transported than liquid or gaseous fuels

Question 34

pros of natural gas

Answer 34

• easy to transport through pipes
• relatively high energy content
• more efficient than coal for energy production

Question 35

cons of natural gas

Answer 35

• non-renewable
• limited reserves
• polluting (but less than coal and petrol)

Question 36

pros of biogas

Answer 36

• renewable
• CO2 adsorbed during photosynthesis offsets some CO2 released during combustion
• low running costs

Question 37

cons of biogas

Answer 37

• low energy content
• supply of waste raw materials limited

Question 38

pros of petrol

Answer 38

• high energy content
• ease of tansport

Question 39

cons of petrol

Answer 39

• non-renewable
• polluting (less than coal)
• limited reserves

Question 40

pros of LPG

Answer 40

• low cost
• easily separated from natural gas
• relatively high energy content

liquified petrolium gas

Question 41

cons of LPG

Answer 41

• non-renewable
• polluting (less than coal)

Question 42

advantages of biodiesel

Answer 42

• lower net CO2 emissions
• no sulfur tf zero SO2 emissions
• burns more completely bc of oxygen present (prescene of C=O makes it easier to oxidise thus combust)

Question 43

disadvantages of biodiesel

Answer 43

• hygroscopic due to presence of ester link -> H2O can be suspended in mixture
• temp at which crystals form is higher -> poor fuel flow due to increased viscosity at lower temps
• cloud point is higher -> fuel flow and combustion is poor at lower temps
• presence of C=O means fuel is more susceptible to oxidation -> lower amount of nrg released during combustion

Question 44

why must water be removed when producing biodiesel

Answer 44

it makes the fuel less efficient

Question 45

in alkanes, as the C:H ratio increases

Answer 45

energy density decreases

Question 46

viscosity

Answer 46

viscosity defines a fluid’s resistance to flow. The higher the viscosity of a liquid, the thicker it is and the greater the resistance to flow

Question 47

as flashpoint increases, viscosity …

Answer 47

increases

Question 48

how can hydogen be generated on water

Answer 48

electrolysis of water using energy from solar energy to power the electrolytic reaction

Question 49

coal seam gas

Answer 49

• mostly methane
• found naturally in commerical quantities near coal deposits