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C12 > Obtaining Energy from Fuels/Fuel Choices > Flashcards

Obtaining Energy from Fuels/Fuel Choices Flashcards

1
Q

Compare and contrast stored energy in fuels and chemicals

A

Chemicals - contain stored energy

Fuels - can release stored energy easily

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2
Q

State what fuels provide

A

Energy

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3
Q

Define fuel

A

Substance that can be reacted with other substances to lead to the release of energy that can be harnessed for a specific purpose

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4
Q

State what the SI unit of energy is

A

Joule (J)

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5
Q

Define non-renewable resources

A

Those that are used faster than they can be replaced

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6
Q

Provide 3 examples of non-renewable fuels

A
  1. Coil
  2. Oil
  3. Gas
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7
Q

State what reserves of fossil fuels can be classified as

A

Limited

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8
Q

Describe how fossil fuels form

A

Formed from ancient plants, animals and microorganisms

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9
Q

State the energy source of fossil fuels

A

Chemical energy retained post-photosynthesis

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10
Q

State what chemical energy in fossil fuels can be considered

A

Trapped solar energy

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11
Q

Fossil fuel formation occurs over ________ of years

A

Millions

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12
Q

Outline the energy content of (black vs brown) coal

A

Brown < Black

Lowest of all fossil fuels (approx. 30MJ/kg)

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13
Q

Outline the renewability of coal

A

Non-renewable

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14
Q

Outline the environmental impacts of sourcing coal

A
  • wildlife habitat destruction due to land clearing

- contamination of underground water deposits by heavy metals via mine wastewater

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15
Q

Outline the environmental impacts of combusting coal

A
  • production of greenhouse gases CO2
  • nitrogen and sulphur oxides react with water to form acid rain
  • nitrogen oxides react with air at ground level to form ozone (contributing to photochemical smog)

Impacts similar to crude oil

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16
Q

Compare and contrast black and brown coal

A

Black coal contains less water and a greater percentage of carbon than brown coal - therefore, it has a higher heat value (making it economical to mine)

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17
Q

Outline the chemical composition of coal

A

Hydrocarbons, water, nitrogen, sulfur

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18
Q

Outline the renewability of crude oil

A

Non-renewable

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19
Q

Outline the chemical composition of crude oil

A

Hydrocarbons (mostly members of homologous series of alkanes), nitrogen and sulfur

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20
Q

State the process used to refine crude oil

A

Fractional distillation

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21
Q

State what the products of crude oil fractional distillation are

A
  • LPG
  • Petrol
  • Kerosene
  • Diesel
  • Fuel oil
  • Petroleum jelly
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22
Q

Outline the energy content of crude oil fractional distillation products

A

Greater than coal, less than petroleum gas

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23
Q

Outline the environmental impacts of sourcing crude oil

A
  • habitat destruction (smaller scale to coal mining)
  • water contamination via fracking
  • oil spills during extraction below seabed
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24
Q

Outline the environmental impacts of combusting crude oil

A
  • production of greenhouse gas CO2
  • nitrogen and sulphur oxides react with water to form acid rain
  • nitrogen oxides react with air at ground level to form ozone (contributing to photochemical smog)

Impacts similar to coal

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25
Q

State whether crude oil is a useful fuel source

A

No, but it contains many useful compounds

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26
Q

Outline the chemical composition of petroleum gas

A

Propane and butane

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27
Q

Outline the renewability of petroleum gas

A

Non-renewable

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28
Q

Outline the energy content of petroleum gas

A

Highest of all fossil fuels (approx. 56MJ/kg)

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29
Q

Outline the environmental impacts of sourcing petroleum gas

A
  • habitat destruction via land clearing (smaller scale to coal)
  • gas leaks (methane potent greenhouse gas - 10x more powerful than CO2)
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30
Q

Outline the environmental impacts of combusting petroleum gas

A
  • production of greenhouse gas CO2

Releases less greenhouse gases/unit energy generated than coal & oil

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31
Q

Outline the renewability of coal seam gas

A

Non-renewable

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32
Q

Outline the energy content of coal seam gas

A

Highest of all fossil fuels (like petroleum gas)

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33
Q

Outline the chemical composition of coal seam gas

A

Methane

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34
Q

Outline the environment impacts of sourcing coal seam gas

A
  • habitat destruction via land clearing for drilling
  • gas leaks of methane
  • water contamination via fracking
  • depletion of groundwater sources
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35
Q

Outline the environmental impacts of combusting coal seam gas

A
  • production of greenhouse gas CO2

Releases less greenhouse gases/unit energy generated than coal & oil

Similar to petroleum gas

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36
Q

State how coal is sourced

A

Open cut mining

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37
Q

State how crude oil is sourced

A

Drilling through bottom of seabed/landmass

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38
Q

State from what petroleum gas is derived from

A

Wet natural gas or crude oil

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39
Q

State how petroleum gas is sourced

A

Drilling

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40
Q

State from what coal seam gas is derived

A

Wet natural gas

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41
Q

State how coal seam gas is sourced

A

Fracking of wet coal deposits underground

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42
Q

Compare and contrast wet natural gas and coal seam gas location

A

Wet natural gas - deposited in ‘bubbles’ underneath rocks

Coal seam gas - mixed within deposits of wet coal underground known as coal seams

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43
Q

Outline the chemical composition of ethanol

A

CH3CH2OH

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44
Q

State how bioethanol is produced

A

Fermentation of glucose by yeast cells

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45
Q

Outline the energy content of bioethanol

A

Similar to coal

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46
Q

Outline the environmental impacts of sourcing bioethanol

A
  • habitat clearing causing ecosystem changes that may be disadvantageous for wildlife
    However, existing plantations can be utilised
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47
Q

Outline the environmental impacts of combusting bioethanol

A
  • net production of CO2 into atmosphere

Similar to biodiesel

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48
Q

Outline the chemical composition of biodiesel

A

Mixture of fatty acid methyl esters (produced via modification of triglycerides)

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49
Q

Outline the energy content of biodiesel

A

Similar to petrol and diesel

50
Q

Outline the environmental impacts of combusting biodiesel

A
  • net production of CO2 into atmosphere

Similar to bioethanol

51
Q

Outline the environmental impacts of sourcing biodiesel

A
  • habitat clearing causing ecosystem changes that may be disadvantageous for wildlife
    However, existing plantations can be utilised
52
Q

Outline the energy content of biogas

A

Comparable to petroleum and coal seam gas

53
Q

Outline the chemical composition of biogas

A

Mixture of gases, primarily methane and some CO2

54
Q

Outline the renewability of biogas

A

Renewable

55
Q

Outline the renewability of bioethanol

A

Renewable

56
Q

Outline the renewability of biodiesel

A

Renewable

57
Q

Outline the environmental impacts of sourcing biogas

A

Minimal if existing plantations are utilised or especially if sourced from landfill/sewage treatment plants

58
Q

Outline the environmental impacts of combusting biogas

A

Carbon neutral
If methane is extracted from landfill/sewage treatment plants, this highly potent greenhouse gas will be replaced with CO2 (10 times less powerful)

59
Q

State how biodiesel is derived

A

Triglycerides found in vegetable oil extracted from crops are converted into FAMEs via transesterification

60
Q

Describe the process of transesterifcation

A

Triglycerides mixed with a mixture of KOH (catalyst) dissolved in methanol (reactant)

61
Q

State from what biogas can be sourced

A
  • Landfill (anaerobic decomposition of organic matter to produce methane)
  • Sewage treatment plants (as above)
  • Biomass (anaerobic digestion of decaying organic matter)
62
Q

Describe petrodiesel

A

One of the products of the fractional distillation of oil

63
Q

State whether or not petrodiesel is a pure substance

A

No. 75% alkanes and 25% aromatic hydrocarbons.

64
Q

Describe aromatic hydrocarbons

A

Contain molecules made of six-membered carbon rings with alternating single and double bonds

65
Q

State the range in which alkanes composing petrodiesel are found

A

C10H22 - C15H32

66
Q

Compare and contrast the flow along fuel lines of biodiesel and petrodiesel

A

Biodiesel more viscous than petrodiesel

thus, doesn’t flow as easily through fuel lines/filters

67
Q

Compare and contrast the cloud point of biodiesel and petrodiesel

A

Biodiesel has a higher cloud point than petrodiesel

68
Q

Describe viscous

A

Measure of liquid’s resistance to flow (thickness)

69
Q

Describe cloud point

A

Temperature at which small crystals start to form

70
Q

Describe hygroscopicity

A

The ability of a substance to absorb moisture from the air

71
Q

Compare and contrast the hygroscopicity of biodiesel and petrodiesel

A

Biodiesel has a significantly higher hygroscopicity than petrodiesel

72
Q

Compare and contrast the environmental impacts of biodiesel and petrodiesel

A 
Combustion of biodiesel:
- lower production of CO
- lower emission of particular matter
- lower emission of unburned hydrocarbons (which could cause photochemical smog)
- higher emission of nitrogen oxides
- lower emission of sulphur oxides
to petrodiesel
73
Q

Compare and contrast the length of petrodiesel and biodiesel molecules

A

Petrodiesel molecules are generally smaller than biodiesel molecules

74
Q

Compare and contrast the sources of petrodiesel and biodiesel

A

Petrodiesel - derived from crude oil which is mined on land/at sea
Biodiesel - derived from crops (increased yield requires intensive farming)

75
Q

Compare and contrast the environmental impacts of producing petrodiesel and biodiesel

A

Petrodiesel - oil refineries produce significant emissions via excess hydrocarbon combustion
Biodiesel - less emissions, however farm machinery produces CO2, high-quality farmland is used for fuel production which deteriorates soil

76
Q

Describe the effect of cold temperatures of fuel viscosity

A

Petrodiesel - flow mostly continues at low temp

Biodiesel - flow stops at high cloud point

77
Q

State some solutions to hygroscopicity and high cloud point of biodiesel

A
  • additives need to be added to motor fuel containing high levels of biodiesel
  • service stations need to keep pumps for biodiesel warmer than surroundings
  • high quality seals/fuel lines may be required
  • biodiesel cannot be stored for a long period of time due to likelihood of biodegradation
78
Q

State the issues associated with hygroscopic fuels

A

If water content is high, combustion can not efficiently occur

79
Q

Describe biofuels

A

Fuels derived from plant materials such as grains, sugar cane, vegetable waste and vegetable oils

80
Q

Provide 3 examples of renewable fuels

A
  1. Biogas
  2. Bioethanol
  3. Biodiesel
81
Q

Describe renewable resources

A

Natural resources that provide energy that can be constantly replenished

82
Q

State how bioethanol is produced

A

Fermentation of sugars

83
Q

Provide the chemical fermentation reaction of glucose

A

C6H12O6 - > 2CH3CH2OH + 2CO2

84
Q

State how biodiesel is produced

A

Reacting vegetable oils/fats with an alcohol

85
Q

State how biogas is produced

A

Anaerobic decomposition of organic matter

86
Q

State what is generally produced in the transesterification of vegetable oils/fats

A

Glycerol

87
Q

State what vegetable oils and fats contain mixtures of

A

Saturated
Monosaturated
Polysaturated triglycerides

88
Q

Outline the basic structure of a triglyceride molecule

A

Each triglyceride molecule has three different fatty acid ‘tails’ attached to a glycerol backbone

89
Q

State what is produced by the alcohol used in the transesterification of fatty acids if methanol is used

A

FAMEs are produced

90
Q

Define FAMEs

A

Fatty acid methyl esters

91
Q

State what the transesterification reaction requires

A

A catalyst to help ‘snip’ the links between the glycerol backbone and three fatty acids

92
Q

Summarise the transesterification reaction using a word equation

A

3 methanol molecules + 1 triglyceride molecule - > 3 fatty acid methyl ester molecules + 1 glycerol molecule

93
Q

Describe structure of unsaturated fatty acid

A

Double C=C bond which causes kink/bend in chain

94
Q

Describe structure of saturated fatty acid

A

Single C-C bond which does not cause kink/bend in chain

95
Q

Outline the chemical composition of glycerol

A

C3H8O3

96
Q

State what chemical structure specific to glycerol allows it react with the COOH group at the end of three fatty acid molecules

A

Three OH groups

97
Q

State what the purpose of three OH groups on a glycerol molecule is

A

Enable reactions with the COOH group at the end of the three fatty acid molecules (and the formation of the triglyceride molecule).

98
Q

Provide the general formula of a fatty acid

A

CnH2n+1COOH

99
Q

State the key structural difference between a biodiesel molecule and a molecule of petrodiesel

A

Biodiesel has two oxygen atoms within it

100
Q

State the chemical composition of the two layers of biodiesel fuel

A

Top layer - fuel (e.g. ethanol)

Bottom layer - glycerol and potassium hydroxide and unreacted fuel (e.g. unreacted ethanol)

101
Q

Define flash point

A

Lowest temp which can yield sufficient vapor to ignite air near flammable liquid’s surface.

102
Q

State whether the conversion of liquid water to gaseous water involves the input of energy

A

Yes. Involves energy input.

103
Q

Provide the relationship between the magnitude of the flash point and ease of material ignition

A

The lower the flash point, the easier it is to ignite the material.

104
Q

Compare and contrast the flash point of biodiesel and petrodiesel

A

Biodiesel has greater flash point than petrodiesel

105
Q

Compare and contrast the length, polarity, intermolecular forces of petrodiesel and biodiesel

A

Petrodiesel - small, non-polar molecules (weak dispersion forces between)
Biodiesel - long hydrocarbon chain, polar molecules, two highly electronegative oxygen atoms (dipole-dipole bonds)

106
Q

State the effect of polar bonds in biodiesel

A

Increase viscosity
Increases melting point
Increases hygroscopicity

107
Q

Provide the approximate length of a biodiesel chain

A

Approx. 12 to 22 carbon molecules

108
Q

Provide the approximate length of a petrodiesel chain

A

Approx. 10 to 15 carbon molecules

109
Q

State what many petrodiesel deposits are contaminated with

A

H2S, sulfur compounds and nitrogen oxides

110
Q

Explain why oxygen exists in biodiesel

A

Petrodiesel - produced anaerobic conditions (remove oxygen from dead organic matter)

Biofuels - transesterification (fats and oils from living organic matter are broken to yield long molecules containing oxygen)

111
Q

Describe cetane number

A

Measure of the quality of combustion of a fuel within the engine of a vehicle

112
Q

Compare and contrast the cetane number of biodiesel and petrodiesel

A

Petrodiesel < Biodiesel

113
Q

Compare and contrast the energy density of petrodiesel and biodiesel

A

Petrodiesel > Biodiesel

114
Q

Compare and contrast the oxidative stability of petrodiesel and biodiesel

A

Petrodiesel > Biodiesel (less stable during long term storage)

115
Q

Describe the oxidative stability

A

Measure of oil or fat resistance to oxidation

116
Q

Compare and contrast the nitric oxide and sulfur emissions of biodiesel and petrodiesel

A

Biodiesel produces less sulfur emissions but more nitric oxide emission than petrodiesel.

117
Q

Compare and contrast lubrication of biodiesel and petrodiesel

A

Biodiesel > Petrodiesel

118
Q

Compare and contrast burn efficiency of biodiesel and petrodiesel, referencing chemical composition

A

The extra oxygen provides more efficient burn - less CO produced because of greater amount of oxygen that can produce CO2

119
Q

Compare and contrast degradation of biodiesel and petrodiesel, referencing chemical composition

A

Ester group allows biodiesel to be taken up by microorganisms/exposed to light which causes spontaneously degradation
Advantage - spills
Disadvantage - storage

120
Q

Compare and contrast the charge of biodiesel and petrodiesel, referencing chemical composition and arrangement

A

Oxygen atoms make biodiesel molecule polar - end of molecule near oxygen has a net negative change/end farthest has a net positive charge.
- polarity makes it easier for biodiesel to form a crystal structure (when freezing - reducing cloud point)

121
Q

Compare and contrast the corrosive characteristics of biodiesel and petrodiesel, referencing chemical composition and arrangement

A

Polarity of biodiesel increases likelihood of reactions with surrounding material
Thus, biodiesel can speed up corrosion of metals - decreasing lifespan of some engine components.

C12 (7 decks)

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