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Chemistry - Units 3 & 4 > Ch 1 - Carbon based fuels > Flashcards

Ch 1 - Carbon based fuels Flashcards

1
Q

fuel

A

a substance that stores chemical energy, and can be combusted in air or oxygen to release useful energy

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2
Q

secondary fuel

A

a fuel that is produced from another energy source

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3
Q

renewable

A

(with reference to energy sources) energy sources that can be produced faster than they are used

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4
Q

fossil fuels

A

Carbon-based fuels formed from once-living organisms over millions of years

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5
Q

coal

A

the most plentiful fossil fuel; it is formed from the combined effects of pressure, temperature, moisture and bacterial decay on vegetable matter over several hundred million years, and is made up of carbon, oxygen, water and traces of other elements

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6
Q

brown coal

A

Coal with a significant amount of water in it, and less energy content compared to black coal (10-18 kJ/g). Formed over a period of 23-60 million years. Is a heavy pollutant

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7
Q

megajoules

A

a unit of energy; one megajoule (MJ) is equal to 1 × 10^6 joules (J)

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8
Q

Coldry Process

A

a patented process that changes the naturally porous form of brown coal to produce a dry, dense pellet and release moisture trapped in the pores (making energy production more efficient), via a process called ‘brown coal densification’

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9
Q

black coal

A

Coal subjected to high temperatures and pressure for longer than brown coal (145-299 million years) and as a result contains less water and more energy per kilogram (17-25kJ/g)

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10
Q

natural gas

A

a source of alkanes (mainly methane) of low molecular mass, formed with oil in muds that are low in oxygen and rich in organic matter (typically ancient marine organisms) - (42-55 kJ/g)

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11
Q

adsorbed

A

the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface

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12
Q

aquifers

A

an underground rock layer that contains water; this groundwater can be extracted using a well

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13
Q

fracking

A

the process of pumping a large amount of fluid, mainly water, under high pressure into a drilled hole, in order to break rock so that it will release gas or oil - may lead to pollution of groundwater, or cause earth tremors

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14
Q

petroleum

A

(aka crude oil) - a viscous, oily liquid composed of crude oil and natural gas that was formed by geological processes acting on marine organisms over millions of years; it is a mixture of hydrocarbons used to manufacture other fuels (petrol, diesel, etc) and many other chemicals - refined via fractional distillation

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15
Q

kerosene

A

a mixture of hydrocarbons with molecules containing between 10 and 15 carbon atoms

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16
Q

liquified petroleum gas (LPG)

A

a hydrocarbon fuel that consists mainly of propane and butane

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17
Q

petrol (aka gasoline)

A

A petrochemical fuel. Mixture of small hydrocarbons ranging from 4-12 carbon atoms per molecule (generally 5). Contains approximately 44-46 MJ kg-1 (44-46 kJ/g

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18
Q

alkanes

A

the family of hydrocarbons containing only single carbon-carbon bonds

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19
Q

alkenes

A

the family of hydrocarbons that contain at least one carbon-carbon double bond

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20
Q

cyclic hydrocarbons

A

also known as ring structures, because the carbon chain is a closed structure without open ends

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21
Q

Diesel (aka petrodiesel)

A

A petrochemical fuel. Mixture of organic hydrocarbons of 12-14 carbon atoms. Used as a transport fuel, mainly for large vehicles. Has a similar energy content per gram to petrol, but a higher density and combusts more efficiently -> more energy per litre. - (42-46 (kJ/g)

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22
Q

global warming

A

a gradual increase in the overall temperature of Earth’s atmosphere

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23
Q

biofuels

A

a renewable, carbon-based energy source formed in a short period of time from living matter (waste plant and animal matter).

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24
Q

biogas

A

a fuel produced from the anaerobic fermentation of organic matter. (25-53 kJ/g depending on methane content) - commonly obtained by fermenting livestock manure in an airtight digester, and then collecting and storing the biogas in a tank

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25
biodiesel
a fuel produced from vegetable oil or animal fats and combined with alcohol, usually methanol, using heat or a catalyst (KOH or NaOH) via transesterification - (40 kJ/g)
26
fatty acids
long-chain carboxylic acids, usually containing an even number of 12-20 carbon atoms
27
glycerol
an alcohol; it is a non-toxic, colourless, clear, odourless and viscous liquid that is sweet-tasting and has the semi-structural formula CH2OHCH(OH)CH2OH
28
transesterification
the conversion of one ester (triglyceride) into another ester (biodiesel)
29
bioethanol
ethanol produced by fermenting sugar from plants, such as sugarcane or waste wheat starch, and used as an alternative to petrol - (30 kJ/g)
30
How is bioethanol produced
1 - Fermentation - Yeast ferments sugars to make energy (C6H12O6(aq) -> 2C2H5OH(aq) + 2CO2 2 - Distillation - ethanol and water separated by heating the mixture above ethanol's boiling point (78.3°C)
31
yeast
a single-celled fungus which produces ethanol as a result of anaerobic fermentation.
32
efficiency
(of energy conversion) the ratio between useful energy output and energy input
33
How do you get a value for energy efficiency? (%)
%efficiency = (energy obtained in desired form)/(energy available before conversion) x 100 aka -> % = output/input
34
sustainable energy
energy that meets present needs without compromising the ability of future generations to meet their own needs
35
non-renewable
(with reference to energy sources) energy sources that are consumed faster than they are being formed
36
particulates
solid and liquid particles small enough to be suspended in the atmosphere
37
carbon neutral
no net release of carbon dioxide into the atmosphere
38
Advantages of using coal:
- Cheap - Large reserves in Australia
39
Disadvantages of using coal:
- Heavy pollutants — SO2, NOx, particulates - Inefficient/highest CO2 emissions produced per MJ energy
40
Advantages of using natural gas:
- High energy content - High energy efficiency - Less pollutants compared to coal
41
Disadvantages of using natural gas:
- Moderate CO2 emissions - CSG involves fracking - Leaks can cause explosions, therefore storage tanks and distribution networks are constantly monitored
42
Advantages of using petrol and diesel:
- Infrastructure for fuel production and distribution is established - High energy content
43
Disadvantages of using petrol and diesel:
- Medium to high CO2 emissions - CO emissions in populated areas
44
Advantages of using biogas:
- Reduces impact on the greenhouse effect as unburnt CH4 has a bigger impact than CO2 released once combusted - Can be made from organic waste from farms and homes (green bin)
45
Disadvantages of using biogas:
- Lower energy content and inefficient if not upgraded/needs to be upgraded to increase efficiency (percentage of methane)
46
Advantages of using biodiesel:
- Reduced pollutant emissions compared to petrodiesel - requires less energy and has fewer emissions than producing bioethanol
47
Disadvantages of using biodiesel:
- Can be problematic in lower temperatures - Production requires land, which can result in deforestation or land being used to make fuel instead of food
48
Advantages of bioethanol:
- Can be used in petrol blends such as E10 (10% ethanol in petrol) for existing car engines without modification - Higher octane rating than petrol so provides more power - Cheap and relatively easy to produce compared to other biofuels
49
Disadvantages of bioethanol:
- Lower energy content per mass - Requires land to grow crops
50
greenhouse effect
a natural process that warms Earth’s surface; when the Sun’s energy reaches Earth’s atmosphere, some of it is reflected back to space, and the rest is absorbed and re-radiated by greenhouse gases
51
greenhouse gases
gases that contribute to the greenhouse effect by absorbing infrared radiation
52
enhanced greenhouse effect
the effect of increasing concentrations of greenhouse gases in the atmosphere as the result of human activity
53
climate change
changes in various measures of climate over a long period of time
54
thermochemistry
the branch of chemistry concerned with the quantities of heat evolved or absorbed during chemical reactions
55
chemical energetics
a branch of science that deals with the properties of energy and the way it is transformed in chemical reactions
56
potential energy
energy that is stored, ready to do work
57
kinetic energy
energy associated with movement, in doing work
58
enthalpy
a thermodynamic quantity equivalent to the total heat content of a system
59
change in enthalpy
the amount of energy released or absorbed in a chemical reaction -> Change in enthalpy (Δ H) = enthalpy of products (Hp) - enthalpy of reactants (H'R)
60
heat of reaction
the heat evolved or absorbed during a chemical reaction taking place under conditions of constant temperature and of either constant volume or, more often, constant pressure
61
heat of solution
the change in enthalpy when one mole of any substance dissolves in water.
62
heat of neutralisation
the change in enthalpy when an acid reacts with a base to form one mole of water.
63
heat of vapourisation
the change in enthalpy when one mole of liquid is converted to a gas.
64
heat of combustion
the enthalpy change when a substance burns in air, and is always exothermic.
65
exothermic
describes a chemical reaction in which energy is released to the surroundings (ΔH < 0)
66
endothermic
describes a chemical reaction in which energy is absorbed from the surroundings (ΔH > 0)
67
standard laboratory conditions
100 kPa and 25 °C
68
kilojoules
a unit of energy; one kilojoule (kJ) is equal to 1 × 10^3 joules (J)
69
thermochemical equation
balanced stoichiometric chemical equations that include the enthalpy change
70
oxidation
loss of electrons; an increase in the oxidation number
71
energy profile diagrams
a graph or diagram that shows the energy changes involved in a reaction from the reactants through the intermediate stages to the products
72
activation energy (Ea)
the minimum energy required by reactants in order to react
73
dioxins
highly toxic compounds formed from industrial processes and incomplete combustion of organics
74
carbohydrates
the general name for a large group of organic compounds occurring in food and living tissues; includes sugars, starch and cellulose (16 kJ/g)
75
fats
a triglyceride formed from glycerol and three fatty acids (37 kJ/g)
76
proteins
large molecules composed of one or more long chains of amino acids (17 kJ/g)
77
metabolism
the chemical processes that occur within a living organism to maintain life
78
lipids
substances such as fats, oils and waxes that are insoluble in water
79
triglycerides
fats and oils formed by a condensation reaction between glycerol and three fatty acids
80
urea
a molecule synthesised in the liver to remove ammonia from the body
81
legumes
plants that produce pods with a seed inside
82
monosaccharides
the simplest form of carbohydrate, consisting of one sugar molecule
83
disaccharides
two sugar molecules (monosaccharides) bonded together
84
polysaccharides
more than ten monosaccharides bonded together
85
fructose
a pentose monosaccharide
86
starch
a condensation polymer of glucose
87
cellulose
the most common carbohydrate and a condensation polymer of glucose; humans cannot hydrolyse cellulose, so it is not a source of energy
88
dietary fibre
non-starch polysaccharides in both water-soluble and water-insoluble forms
89
photosynthesis
in the presence of light, carbon dioxide + water → glucose + oxygen | 6CO2(g) + 6H2O(l) -> CC6H12O6(aq) + 6O2(g) ΔH = +2.8 x 10^3 kJ/mol
90
chlorophyll
a series of green pigments that enable plants to capture sunlight for photosynthesis
91
cellular respiration
the process that occurs in cells to oxidise glucose in the presence of oxygen to carbon dioxide, water and energy | C6H12O6(aq) + 6O2(g) -> 6CO2(g) + 6H2O(l) ΔH=-2860 kJ/mol
92
anaerobic respiration
the breakdown of glucose in the absence of oxygen | C6H12O6(aq) -> 2C2H5OH(aq) + 2CO2(g)
93
lactic acid
an organic acid, C3H6O3, present in muscle tissue as a by-product of anaerobic respiration
94
ethanol
an alcohol with two carbons produced from fermentation of glucose by yeast
95
biomethane
produced by a process called upgrading, where gases other than methane present in biogas are removed. Also produced by breaking down solid biomass at high temperatures in an oxygen-deficient environment, and then using a catalyst to combine CO/CO2 and H2 to make methane.
96
feedstocks
raw materials used to supply or fuel a machine or industrial process
97
Complete combustion
occurs in excess oxygen Thermochemical equation at SLC: Fuel(l or g) + O2(g) -> CO2(g) + H2O(l at SLC but generally g due to high heat of combustion) ΔH = negative
98
incomplete combustion
oxygen is the limiting reactant - results in many pollutants and less energy per kg of fuel fuel(l or g) + O2 -> CO(g) or C(s) + H2O(l at SLC but generally g due to high heat of combustion)

Chemistry - Units 3 & 4 (3 decks)

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