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Y12 Chem > Fuels > Flashcards

Fuels Flashcards

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1
Q

What is a fuel?

A

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

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2
Q

Which of the following are examples of fossil fuels?
a) Methane
b) Octane
c) Biodiesel
d) Bioethanol
e) CSG (coal seam gas)
f) Liquid petroleum gas (LPG)
g) Natural gas
h) Biogas
i) Diesel/petrodiesel

A

a) Methane
b) Octane
e) CSG (coal seam gas)
f) Liquid petroleum gas (LPG)
g) Natural gas
i) Diesel/petrodiesel

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3
Q

Describe the greenhouse effect

A

the process of the warming of the Earths lower atmosphere due to the increased quantities of gases of ‘greenhouse gases’ such as carbon dioxide, water vapour and methane in the air

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4
Q

a) What is a biofuel.
b) Name three biofuels

A

a) a fuel sourced from biomass / organic matter

b) biogas, bioethanol, biodiesel

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5
Q

Define fossil fuel.

A

a natural fuel formed in the earth from plant or animal remains

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6
Q

What is petrodiesel?

A

A liquid hydrocarbon fossil fuel obtained from crude oil

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7
Q

Which type of fuel has a lower energy content; biofuels or their fossil fuel equivalent, i.e. biogas or CH4 sourced from fossil fuel?

A

biofuels have a lower energy content compared to their fossil fuel equivalents, i.e. CH4 sourced from fossil fuel with have a higher energy contact than biogas

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8
Q

State if fuels generally have a high or low boiling point, flashpoint, flammability

A

Fuels generally have low boiling point, low flashpoint, high flammability

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9
Q

State some storage considerations for a fuel

A

store away from naked flames (because fuels are flammable)
store in well ventilate areas (to avoid suffocation / asphyxiation)

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10
Q

State some safety considerations for dealing with fuels with a low boiling point

A

use / store away from naked flame (as the fuels will be flammable)
work in well ventilated areas (as vapours can be harmful)
avoid contact to the skin and eyes by wearing safety glasses, labcoat and gloves if required

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11
Q

State the intermolecular bonding that can occur between hydrocarbons

A

dispersion forces

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12
Q

Explain why the boiling point of pentane is higher than he boiling point of ethane

A

Comment of the structure of the molecules, then identify the intermolecular bonding before linking to the question.

Because pentane (C5H12) is a longer chain hydrocarbon compared to ethane (C2H4),
Then pentane has a larger number of dispersion forces acting between the molecules
Therefore a greater level of kinetic energy is required to disrupt the forces between pentane, hence pentane has a higher boiling point.

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13
Q

Explain why the boiling point of propane is lower than the boiling point of ethanol

A

Comment of the structure of the molecules, then identify the intermolecular bonding before linking to the question.

Because ethanol contains a hydroxyl group whereas propane is a straight chain hydrocarbon
Then hydrogen bonds form between the hydroxyl (-O-H) groups of ethanol molecules whereas only dispersion forces exist between propane molecules
Therefore the stronger intermolecular bonds between ethanol molecules require a greater kinetic energy to overcome causing ethanol to have a higher boiling point

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14
Q

Define the term flashpoint

A

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

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15
Q

Explain why the flashpoint of propan-1-ol is higher than the flashpoint of propan-2-ol

A

Comment on the structure of the molecules, then identify the intermolecular bonding before linking to the question

Because propan-2-ol has branched chain molecules whereas propan-1-ol has straight chin molecules
Then the propan-1-ol molecules are able to fit closer together allowing the dispersion forces between propan-1-ol molecules to be stronger than the dispersion forces between propan-2-ol molecules as the forces are acting over a shorter distance
Therefore greater energy is required to disrupt the bonds between panpan-1-ol molecules causeing it to be less easily vapourised.

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16
Q

Define renewable resource

A

one that can be replenished at a rate as quickly or faster than the rate they are being consumed / used

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17
Q

Define non-renewable resource

A

One that is NOT able to be replenished at a rate greater than or equal to the rate it is being consumed / used

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18
Q

Identify three examples of renewable fuels

A

Biogas,
Bioethanol,
Biodiesel

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19
Q

Identify three examples of non-renewable fuels

A

Methane,
natural gas,
Coal,
Coal-seam gas,
Diesel / Petrodiesel

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20
Q

Explain why biofuels produced from plants are considered to be almost carbon neutral / have approximately zero net impact on atmospheric carbon dioxide.

A

Because plants undergo photosynthesis whilst they grow, they absorb carbon dioxide from the atmosphere
Then when the plant is converted into a biofuel and burned, the carbon dioxide absorbed by the plant is released back into the atmosphere
Therefore there is not NET release of carbon dioxide in to the atmosphere

21
Q

What are some advantages of using coal as a fuel?

A

Large reserves
Relatively high energy content

22
Q

What are some disadvantages of using coal as a fuel?

A

Non-renewable
Increases atmospheric carbon dioxide levels
Less easily transported than liquid or gaseous fuel (as cannot be transported in pipes)
Releases sulfur based pollution into the atmosphere

23
Q

What are some advantages of using natural gas as a fuel?

A

Relatively high energy content
More efficient than coal for electricity production
Easy to transport through pipes

24
Q

What are some disadvantages of using natural gas as a fuel?

A

Non-renewable
Limited reserves
Releases greenhouse gases such as CO2 (but less compared to coal and petrol)

25
Q

What are some advantages of using biogas as a fuel?

A

Renewable
Almost net zero release of atmospheric carbon dioxide because carbon dioxide is absorbed by the plants during photosynthesis
Produced from waste
Reduces waste disposal
Low running costs
zero sulfur emissions
Burns / combusts more completely

26
Q

What are some disadvantages of using biogas as a fuel?

A

Less energy dense compared to fossil fuel alternatives
Supply of waste raw materials is limited
hygroscopic (absorbs water)

27
Q

What are some advantages of using petrol / petrodiesel as a fuel?

A

High energy content
Ease of transport

28
Q

What are some disadvantages of using petrol / petrodiesel as a fuel

A

Non-renewable
Increases atmospheric carbon dioxide levels
Polluting, but less than coal

29
Q

What are some advantages of using bioethanol as a fuel?

A

Renewable
Almost net zero release of atmospheric carbon dioxide because carbon dioxide is absorbed by the plants during photosynthesis
can be made from waste
Burns smoothly
Fewer particulates produced compared to petrol

30
Q

What are some disadvantages of using bioethanol as a fuel?

A

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

31
Q

How is biodiesel formed?

A

Esterification of fats and oils in organic matter (animal products and oils originating from crops). Biodiesel is formed form a reaction between a fatty acid with an alkanol

32
Q

What is the main functional group present in biodiesel

A

ester

33
Q

What is another name commonly used to identify biodiesel

A

methyl ester

34
Q

what are some sources of methane gas?

A

Biogas, natural gas and coal seam gas

35
Q

What is the photosynthesis formula equation?

A

6CO2 + 6H2O -> C6H12O6 + 6O2

36
Q

What is the word equation for photosynthesis?

A

carbon dioxide + water -> glucose + oxygen

37
Q

What is biogas?

A

A mixture of gases (mainly methane) produced by the breakdown of organic matter.

38
Q

How is biogas produced?

A

Biogas is produced from the anaerobic breakdown of biomass / organic matter by bacteria. Examples of biomass include algae, crops, wood, compostable garbage.

39
Q

How is bioethanol produced?

A

by the fermentation of glucose in organic matter by a microorganism called yeast. Example of organic matter include crops such as wheat, corn and sugarcane.

40
Q

Write the word equation and balanced formula equation for the fermentation of ethanol

A

Glucose —–(bacteria)—-> Ethanol + Carbon dioxide

C6H12O6 (aq) ——(bacteria)—->2CH3CH2OH(l) + 2CO2(g)

(note the glucose in the fermentation equation is aq. aqueous)

41
Q

What is a triglyceride composed of?

A

3 fatty acid chains and 1 glycerol molecule, joined via ester links

42
Q

What is produced when a triglyceride reacts with an alkanol such as methanol in the presence of a catalyst?

A

3 biodiesel molecules (methyl esters) and 1 glycerol molecule

43
Q

A triglyceride will react with an alkanol to form biodiesel and glycerol. What is the name of this type of reaction?

A

transesterification

44
Q

What is produced when a fatty acid reacts with an alkanol such as methanol?

A

1 biodiesel molecule (methyl ester) + 1 water molecule

45
Q

Compare the properties of biodiesel versus petrodiesel

A
  • biodiesel has higher viscosity than petrodiesel
  • biodiesel has higher freezing point than petrodiesel
  • biodiesel has higher viscosity particularly at cold temperatures
  • biodiesel is more hygroscopic than petrodiesel
  • biodiesel has higher melting point than petrodiesel
  • biodiesel is less energy dense than petrodiesel
  • biodiesel forms a gel / crystalises at a higher temperature (resulting in increased viscosity and poor flow at lower temps)
  • biodiesel cloudpoint is higher than petrodiesel
  • biodiesel is more likely to oxidise causing a gum-like substance to form in the fuel.
46
Q

compare the production of biodiesel versus petrodiesel

A

Biodiesel is produced from biomass / organic matter which is a renewable energy source where as petrodiesel is produced from fossil fuels which as non-renewable.

Biodiesel requires land and water to produce. This land / water could otherwise be used for food production.
Petrodiesel requires drilling of crude oil. Oil fields / refinaries are prone to oil spills and produce emissions that have a negative affect on the environment.

47
Q

Compare the environmental affect of biodiesel versus petrodiesel

A

Biodiesel produces a lower (almost net zero) net emission of carbon dioxide due to partial offset from the absorption of CO2 whist growing.
whereas
Petrodiesel has a greater net emission of carbon dioxide into the atmosphere

Biodiesel produces fewer particulates and fewer pollutants compared to petrodiesel.

48
Q

Explain how the presence of the polar ester bond in biodiesel affects its properties compared to petrodiesel and how this affects the use of biodiesel

A

The presence of the ester bond causes biodiesel to be more hygroscopic (absorb water) as the ester bond forms hydrogen bonds with water. The presence of water decreases the heat of combustion of the fuel, increases the likelihood of corrosion of fuel system and increases smoke produced when the fuel burns.

The ester bond results in biodiesel having higher viscosity than petrodiesel as dipole-dipole bonds form between the molecules compared to dispersion bonds between petrodiesel molecules.

The ester bond results in biodiesel being more likely to oxidise causing a gum like substance to form in the fuel. This can block fuel lines and filters. The oxidation results in the fuel becoming more acidic which can lead to corrosion

Y12 Chem (5 decks)

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