Developing fuels Flashcards
1
Q
What is the equation to find the volume at room temperature ?
A
Volume = moles x 24
2
Q
What is the ideal gas equation ?
A
pV = nRT
3
Q
Under what condition does 1 mole of gas have a volume of 24.0 dm3 ?
A
At room temperature and pressure
4
Q
Write a formula you’d use to find out how many moles there are in a volume of gas at RTP ?
A
Moles = volume / 24
5
Q
10 g of calcium carbonate react with excess dilute HCl at RTP to produce calcium chloride, water and carbon dioxide.
CaCO3 + 2HCl –> CaCl2 + H2O + CO2
What is the volume of carbon dioxide ?
A
Use the two equations;
- Moles = Mass / Mr
- Volume = Moles x 24
10 / 100.1 = … no. of moles of CaCO3
Mole ratio of CaCO3 : CO2 = 1 : 1
No. of moles of CaCO3 is equal to the no. of moles of CO2.
Volume of CO2 produced = 2.398 dm3
6
Q
4 dm3 of ethane (C2H6) are burned in 20 dm3 of oxygen to produce carbon dioxide and water vapour.
Write a balanced equation for the reaction ?
A
C2H6 + 3.5O2 –> 2CO2 + 3H2O
7
Q
Magnesium carbonate thermally decomposes to produce magnesium oxide and carbon dioxide. What mass of magnesium carbonate is needed to produce 6.00 dm3 of carbon dioxide at RTP ?
A
Moles = Volume / 24
Mass = Moles x Mr
6.00 / 24 = … moles of carbon dioxide
(6.00/24) x 84.3 = 21.075 g
8
Q
At what temperature will 1.28g of chlorine gas occupy 98.6 dm3, at a pressure of 175 Pa ?
A
PV =nRT
Moles = Mass / Mr
1.28 / 71 = .. no. of moles of chlorine
T = PV / nR
T = 175 x 0.0986 / (1.28 / 71) x 8.314
T = 115.12 K
9
Q
Convert dm3 to m3
A
Divide by 1000
10
Q
Convert cm3 to m3
A
Divide by 10^6
11
Q
What is enthalpy change ?
A
The heat transferred in a reaction at constant pressure. The units are KJ/mol
12
Q
What are enthalpy changes under ?
A
They are under standard conditions. 298 K and 100 KPa
13
Q
What is an exothermic reaction ?
A
Reaction that gives out energy.
The temperature often increases.
It is negative.
14
Q
What is an endothermic reaction ?
A
Reaction that absorbs energy.
The temperature often decreases.
It is positive.
15
Q
What is a bond enthalpy ?
A
The energy needed to break a bond or the energy given out when a bond forms.
16
Q
What is the enthalpy change of reaction ? (equation)
A
Enthalpy change of reaction = Total energy absorbed to break bonds - Total energy released in making bonds.
17
Q
Calculate the overall enthalpy change for this reaction : N2 + 3H2 –> 2NH3
Use the average bond enthalpy values in the table below.
Nitrogen = 945 KJ/mol
H-H = 436 Kj/mol
N-H - Hydrogen = 391 Kj/mol
A
1 x 945 = 945 Kj/mol
3 x 436 = 1308 kj/mol
Total energy absorbed = 945 + 1308 = 2253
6 x 391 = 2346
Total energy released = 2346
Total energy absorbed = Total energy released
2253 - 2346 = -93 kj/mol (exothermic reaction)
18
Q
What is the bond length ?
A
The distance between the two nuclei is the distance where the attractive and repulsive forces balance each other. The stronger the attraction between the atoms, the higher the bond enthalpy and the shorter bond length. (The two positively charged nuclei also repel each other, as do the electrons)
19
Q
Describe the conditions under which standard enthalpy changes are measured ?
A
They are under standard conditions > 298 K and 100 KPa.
20
Q
Is energy taken or released when bonds are broken ?
A
Energy is taken in
21
Q
What states must compounds be in when bond enthalpies are measured ?
A
Gas
22
Q
Why might the figure in a data book for bond enthalpy not be the exact enthalpy change for that type of bond in a particular compound ?
A
The bond enthalpies in a data book are the average bond enthalpies.
23
Q
Explain why the bond enthalpy if C=O in ketones is greater than the bond enthalpy of C-O in alcohols ?
A
In the C=O bond they share 4 electrons, compared to in the C-O bond they only share two electrons. This means that in the C=O bond there is a greater electron density between the two positively charged nuclei, so therefore greater attraction between the nuclei and the electrons.
24
Q
Hydrogen peroxide has the same structure: H-O-O-H. Using the values from the table on the right, calculate the overall enthalpy change for the reaction ?
H2O2 –> H2O + 0.5O2
H-O –> 463 kj/mol
O-O –> 146 kj/mol
O=O –> 498 kj/mol
A
2 x 463 = 926 kj/mol
1 x 146 = 146
Total energy absorbed = 926 + 146 = 1072
2 x 463 = 926 kj/mol
0.5 x 498 = 249 kj/mol
Total energy released = 926 + 249 = 1175
Total energy absorbed to break the bonds - Total energy released to make the bonds
1072 - 1175 = -103 kj/mol (exothermic reaction)
25
What is the standard enthalpy change of reaction ?
The enthalpy change when the reaction occurs in molar quantities shown in the chemical equation, under standard equations.
26
What is the standard enthalpy change of formation ?
The enthalpy change when 1 mole of a compound is formed from its elements in their standard states, under standard conditions.
27
What is the standard enthalpy change of combustion ?
The enthalpy change when 1 mole of a substance is completely burned in oxygen, under standard conditions.
28
What does Hess's law state ?
The total enthalpy change is always the same, no matter which route is taken.
29
What is the activation energy ?
The minimum amount of energy needed to begin breaking the reactant bonds and start a chemical reaction.
30
What is the equation to find the heat absorbed ?
heat absorbed = mass of water x specific heat capacity of water x temperature change.
31
What can you assume about the heat absorbed (q = mcT) equation ?
- All solutions (reactants and products) have the same density as water > this means you can use volume rather than mass ( 1cm3 of water has a mass of 1g).
- Also assume that the specific heat capacity of the solution formed is the same as that for water.
32
What is the standard enthalpy change of neutralisation ?
The enthalpy change when an acid and alkali react together, under standard conditions, to form 1 mole of water.
33
In a laboratory experiment, 1.16g of an organic liquid fuel was completely burned in oxygen. The heat formed during the combustion raised the temperature of 100g of water from 17.5oC to 80oC. Calculate the standard enthalpy of combustion of the fuel. Mr = 58.0
q = mcT
q = 100 x 4.18 x (80.0 - 17.5) = 26125 J
26125 / 1000 = 26.125 KJ
(The standard enthalpy change of combustion involves 1 mole of fuel)
Moles = mass / Mr
1.16 / 58.0 = 0.0200 moles of fuel
26.125 KJ / 0.0200 = -1310 Kj/mol (This is the standard enthalpy change of combustion, and it is negative because combustion is an exothermic reaction.)
34
Why might the enthalpy change we calculated not be the actual enthalpy change figure ?
- Incomplete combustion
- Not be under standard conditions
35
Briefly describe an experiment that could be carried out to find the enthalpy change of combustion of a reaction ?
To find the enthalpy change of combustion of a flammable liquid you burn it - using a spirit burner. As the fuel burns, it heats the water > due to the water absorbing the heat.
36
Why is the enthalpy of combustion determined in a lab likely to be lower than the values shown in a lab book ?
- Incomplete combustion
- May not be under standard conditions
37
What equation is used to calculate the enthalpy change in a calorimetry experiment ?
q = mcT
Amount of heat = mass of water x specific heat capacity x temperature change
38
The initial temperature of 25 cm3 of 1.00 mol/dm3 hydrochloric acid in a polystyrene cup was measured as 19.0oC. This acid was exactly neutralised by 25 cm3 of 1.00 mol/dm3 sodium hydroxide solution.. The maximum temperature of the resulting solution was measured at 25.8oC.
Calculate the standard enthalpy change of neutralisation for the reaction ?
q = mcT
50 x 4.18 x 6.8 = 1421.2 J
1421.2 / 1000 = 1.4212 Kj
Moles = concentration x volume
(25.0 / 1000) x 1 = 0.025 moles of HCl
(25.0 / 1000) x 1 = 0.025 moles of NaOH
1.4212 / 0.025 = - 56. 8 Kj/mol
39
A 50.0 cm3 sample of 0.2 mol/dm copper(II) sulfate solution was placed in a polystyrene beaker gave a temperature increase of
2.00 K when excess zinc powder was added and stirred.
Calculate the enthalpy change when 1 mole of zinc reacts. Assume the solutions's specific heat capacity is 4.18 Jg-1K-1.
The equation is:
Zn + CuSO4 --> Cu + ZnSO4
q = mcT
50 x 4.18 x 2.00 = 418 J
418 / 1000 = 0.418 KJ
Moles = Concentration x volume
(50 / 1000) x 0.2 = 0.01 moles of copper sulfate
0.418 / 0.01 = 41.8 Kj/mol
= - 41.8 KJ/mol (exothermic reaction)
40
What is a catalyst ?
A catalyst speeds up a chemical reaction, by providing an alternative pathway and lowering the activation energy. The catalyst is chemically unchanged at the end of the reaction.
41
What is catalysis ?
Speeding up a chemical reaction by using a catalyst.
42
What can long chain hydrocarbons be cracked into ?
Smaller hydrocarbons (including alkenes)
43
Is the cracking if hydrocarbons random ?
Yes
44
Can the same molecule give different cracking products ?
Yes
45
What is needed in a reaction if a catalyst isn't present ?
Extremely high temperatures and pressures (which are expensive)
46
By passing hydrocarbons vapour over a heated solid catalyst, how does this effect the temperature and pressure ?
Cracking can take place at a much lower temperature and pressure (which will save loads of money).
47
What is a heterogeneous catalyst ?
A catalyst that is in a different physical state from the reactants.
48
How do reactions occur on a heterogeneous catalyst ?
- Reactant molecules bond to the surface of the solid catalyst.
- This is called adsorption.
- The bonds between the reactants molecules are weakened and break up.
- This forms radicals (atoms or molecules with unpaired electrons). These radicals then get together and make new molecules.
- The new molecules are then detached from the catalyst.
- This is called desorption.
49
What happens when the catalysts are poisoned ?
The poison clings to the catalysts surface more strongly than the reactant does. So the catalyst is prevented from getting involved in the reaction it's meant to be speeding up.
50
Explain what a catalyst does ?
A catalyst speeds up a chemical reaction. It provides an alternative pathway with a lower activation energy. It remains chemically unchanged by the end of the reaction.
51
What is a heterogeneous catalyst ?
Is a catalyst that is in a different physical state from the reactants.
52
The following reactions represent an important stage in the industrial manufacture of sulfuric acid.
2SO2(g) + O2(g) --> 2SO3(g)
The catalyst used is V2O5(s). Explain why this is considered a heterogeneous catalyst here ?
The catalyst and the reactants are in different physical states. The catalyst is a solid and the reactants are in a gaseous state.
53
The following reactions represent an important stage in the industrial manufacture of sulfuric acid.
2SO2(g) + O2(g) --> 2SO3(g)
How could you show, experimentally, that V2O5(s) is a catalyst and not a reactant ?
- Find the mass of the catalyst before and after the reaction.
- If the mass stays the same, V2O5 is the catalyst.
54
The following reactions represent an important stage in the industrial manufacture of sulfuric acid.
2SO2(g) + O2(g) --> 2SO3(g)
Platinum catalysts are more efficient than vanadium catalysts but are seldom used because they are susceptible to poisoning by arsenic. Suggest an explanation for how the poisoning happens ?
The arsenic clings more strongly to the platinum catalyst than the reactants do, so the catalyst cannot got involved in the reaction.
55
Crude OIl is a source of fuels and petrochemicals. It's vapourised and separated into fractions using fractional distillation. Some heavier fractions are processed using cracking,
Give one economic reason why a catalyst is used in the cracking process ?
Cracking can be carried out at lower temperatures and pressures when using a catalyst, which can save a lot of money.
56
Crude Oil is a source of fuels and petrochemicals. Its vapourised and separated into fractions using fractional distillation. Some heavier fractions are processed using cracking.
Write an equation for the thermal cracking of dodecane, C12H26.
C12H26 --> C2H4 + C10H22
57
Are alkanes saturated or unsaturated ?
They are saturated hydrocarbons
58
Are alkenes saturated or unsaturated ?
They are unsaturated hydrocarbons
59
What general formula does alkanes have ?
CnH2n+2
60
How many bonds can a carbon atom form with other atoms ?
4 single bonds
61
What general formula does cycloalkanes have ?
CnH2n
62
Are cycloalkanes saturated or unsaturated ?
They are saturated hydrocarbons.
63
What is the general formula does an alkene have ?
CnH2n
64
What do all all alkenes have in common ?
They all have at least one C=C double bond
65
Why are alkenes unsaturated ?
They can bond to extra atoms in addition reactions.
66
Why is the benzene ring more stable then expected ?
The double bond electrons are delocalised around the carbon ring.
67
a) What are structures with benzene ring structures called ?
b) What are other organic compounds
mean ?
a) Arenes or Aromatic compounds
b) aliphatic compounds
68
what is the general formula of alcohols ?
CnH2n+1OH
69
What it the -OH group called ?
Hydroxyl group
70
Name up to 10 the number of carbons and their stem name
meth- = 1
eth- = 2
prop- = 3
but- = 4
pent- = 5
hex- = 6
hept- = 7
oct- = 8
non- = 9
dec- = 10
71
What does arene or aromatic mean ?
Hydrocarbons that contain a benzene ring.
72
What does aliphatic mean ?
It has carbon and hydrogen joined together in chains.
73
How is a sigma bond formed ?
A sigma bond occurs in a single bond. They form when two orbitals overlap, in a straight line, in the space between two atoms.
74
Why are sigma bond strong ?
They give a very high electron density between the two positive nuclei. This forms a covalent bond.
75
How is a pi bond formed ?
A pi bond is formed when two pi orbitals overlap sideways.
76
Which bond, a sigma or pi bond, is
weaker ?
A pi bond is weaker than a sigma bond. This means that a double bond is less than twice as strong as a single bond.
77
Explains what determines the basic shape of a molecule ?
Electron pairs repel each other, so molecules take the shape that allows all the pairs of electrons to get as far from each other as possible.
78
Describe the shape of a molecule of methane ?
One carbon molecule joined by a single bond and 4 hydrogens - CH4. It is a tetrahedral shape, with the bond angle of 109.5 degrees.
79
How does the arrangement of atoms around a carbon atom with only single bonds differ from the arrangement of atoms around a carbon atom that forms a double bond ?
A carbon molecule can only forms 4 bonds. So in a single bond, carbon can have 4 other molecules coming from it, and in a double bond, carbon can have 2 other molecules coming from it.
80
What type of a covalent bonds hold together the atoms in an alkene molecule ?
A single covalent bond
81
What is a structural isomer ?
A molecule that has the same molecular formula, but has a different structural formula.
82
Which bond cannot rotate ?
A double bond
83
Describe the differences between a shortened structural formula, a structural formula and a skeletal formula ?
- Shortened structural formula : Shows the atoms, carbon by carbon, with the attached hydrogens and functional groups.
- Structural formula : Shows how all the atoms are arranged and all the bonds between them.
- Skeletal formula : Shows the bonds of the carbon skeleton only, with any functional groups. The hydrogen and carbon atoms aren't shown.
84
What does the E/Z isomerism ?
The restricted rotation around the C=C double bond
85
What are stereoisomers ?
They have the same shortened structural formula but a different arrangement in space.
86
If the hydrogens are on the same side, which isomerism it is ?
it is a Z - isomer
87
If the hydrogens are on different sides, which isomerism is it ?
It is an E - isomer
88
What is another name for a Z isomer ?
'cis'
89
What is another name for a E isomer ?
'trans'
90
Define the term 'stereoisomers' ?
The same structural formula but a different arrangement in space.
91
Which corresponds to the 'cis-isomer', the E-isomer or Z-isomer ?
Z-isomer
92
Explain why alkenes can have E/Z isomers but alkanes cannot ?
E/Z isomers occur because atoms cannot rotate around C=C double bond, like they can around single bonds. Alkenes contain C=C double bonds and alkanes don't, so alkenes can form E/Z isomers and alkanes can't.
93
What do alkenes join up to form ?
addition polymers
94
How are polymers formed ?
The double bond in alkenes can open up and join together to make long chains.
95
Adding hydrogen to C=C, produces what ?
Alkanes
96
What does the reaction need, in the reaction when you add hydrogen to C=C double bond ?
You need a catalyst, a nickel catalyst and a temperature of 150 degree celsius and a high pressure, or a platinum catalyst at room temperature and pressure.
97
How do you test for C=C double bonds ?
Add bromine water to an alkene, shake, the orange brown solution will decolourise if the solution has a C=C double bond/unsaturated
98
Bromine reacting with an alkene is an example of ... ?
electrophilic addition
99
How do electrophilic reaction are formed ?
The double bonds open up and atoms are added to the carbon atoms. Electrophilic addition reactions happen because the double bond has got plenty of electrons and is easily attacked by electrophiles.
100
What are electrophiles ?
They are electron-pair acceptors, they are attracted to regions with a high electron density.
101
What are the conditions needed when reacting an alkene with water ?
Water and c.H2SO4
102
What are the conditions needed when reacting an alkene with Br2 ?
Room temperature and pressure
103
What are the conditions needed when reacting an alkene with H2 ?
Room temperature and pressure, Platinum catalyst
104
What are the conditions needed when reacting an alkene with HBr ?
c.H2SO4 and NaBr(s), Room temperature and pressure
105
Describe what it is meant by addition polymerisation ?
The double bonds in alkenes can open up and join together to make long chains called polymers.
106
Ethene can undergo a hydrolysis reaction with cold water in the presence of a catalyst.
Name a catalyst that can be used in the above reaction ?
The ethene reacts with concentrated sulfuric acid and water
107
Ethene can undergo a hydrolysis reaction with cold water in the presence of a catalyst.
Describe what happens in the two stages of this reaction ?
The ethene reacts with concentrated sulfuric acid to form ethyl hydrogen sulfate. The ethyl hydrogen sulfate reacts with water to form ethanol.
108
When you burn an alkane completely what do you end up with ?
Carbon dioxide and water (in the form of steam)
109
Is the combustion of an alkene exothermic or endothermic ?
exothermic reaction
110
What is produced when you burn cycloalkanes, alkenes and alcohols completely ?
Carbon dioxide and water
111
What is carbon dioxide ?
A greenhouse gas
112
What does the earth naturally radiate ?
Infrared radiation
113
Examples of greenhouse gases ?
water vapour, carbon dioxide and methane
114
What keeps the earth warm ?
The earth naturally emits infrared radiation. But greenhouse gases in the atmosphere absorbs some of this radiation - keeping the earth warm. This is called the greenhouse effect.
115
Give an example that increases the amount of carbon dioxide in the atmosphere
Burning carbon-based fuels
116
What is the enhanced greenhouse effect
The increase in global temperatures, that is causing the earth to warm up. This leads to problems such as the melting of the polar ice gaps.
117
What is formed when organic compounds burn incompletely ?
Carbon monoxide
118
Is carbon monoxide poisonous
yes
119
What is the impacts of unburnt hydrocarbons ?
- They can contribute to photochemical smog, which can irritate eyes, aggravate respiratory problems and lung damage.
120
What is the impact of sulfur dioxide ?
- It can lead to acid rain. It destroys vegetation and trees, as well as corroding buildings and statues and killing fish in the lakes.
121
What is the impact of particulates ?
- Can cause major health problems. They can settle in peoples lung ab case problems such as decreased lung function and irritation of the airways. CAn also contribute to cardiovascular problems.
122
Are fossil fuels renewable or
non-renewable ?
Non-renewable
123
What are the three major fossil fuels ?
Coal, Oil and natural gas
124
Are fossil fuels easily extracted ?
Yes, they are easily extracted.
125
Do fossil fuels create a large amount of
energy ?
They produce a large amount of energy
126
What are the biggest sources of air pollutants ?
- Transport
- Industry
- Power generation
127
How is sulfur dioxide removed from power station flue gases ? (flue gases are the emissions from industrial exhausts and chimneys)
Calcium oxide
128
How are particulates removed from power station flue gases ?
Wet scrubbers (this capture them in water droplets and from some car exhausts using filters)
129
What do catalytic converters reduce in emissions from vehicles ?
Carbon monoxide
Unburnt hydrocarbons
Sulfur dioxide
Nitrogen oxide
()
130
What is added to petrol to reduce carbon monoxide emissions ?
Oxygenates - they help the fuel to combust fully
131
Why is the amount of carbon dioxide emissions remain high ?
- Our electricity comes from burning fossil fuels
- The no. of cars on the road has steadily increased
132
What are some ideas to reduce the problem of pollution ?
- Governments can change laws
- New vehicles are not allowed to pollute above a certain level, and the yearly MOT inspection includes an emissions test. Catalytic converters have been compulsory on new cars in the UK since 1992.
- Government can tax pollution more highly
- People can reduce the amount of pollution by changing their behavior
133
Are the combustion of alkanes endothermic or exothermic ?
Exothermic
134
Write an equation for the complete combustion of butene ?
C4H8 + 6O2 --> 4CO2 + 4H2O
135
Explain why the increasing amount of carbon dioxide in the atmosphere is a problem ?
The increasing amount of Carbon dioxide is causing the enhanced greenhouse effect and global warming. This causes the earth to warm up slowly and causing a major problem because it is leading to effects like the melting of the polar ice caps.
136
Explain why too many particulates in the atmosphere can be a problem ?
It can cause some major health problems, they can settle in people lungs and cause problems such as decreased lung function and irritation of the airways. They can also contribute to cardiovascular problems.
137
Write a balanced equation for the complete combustion of hexane ?
C6H14 + 9.5O2 --> 6CO2 + 7H2O
138
Write a balanced equation for the incomplete combustion of pentanol ?
C5H11OH + 5O2 --> 5CO + 6H2O
139
Explain why burning an alkane in limited supply of oxygen is potentially dangerous ?
If there is not enough oxygen then incomplete combustion occurs. One of the products of incomplete combustion is carbon monoxide, which is poisonous/toxic.
140
Explain how the burning of fossil fuels in a car engine can lead to photochemical
smog ?
Photochemical smog is a product of unburnt hydrocarbons and nitrogen oxide. Nitrogen and oxygen - from the air - react together to created nitrogen oxide, due to the high temperature and pressures in an engine. Unburnt hydrocarbons and nitrogen oxide react together with sunlight to produce ground-level ozone, which is a major component of smog.
141
State how the levels of pollutants that can
lead to photochemical smog can be
reduced ?
Catalytic converters can remove unburnt hydrocarbons and oxides of nitrogen (nitrogen oxide from an engine).
142
Another problem caused by pollution is acid rain .
Name two pollutants which can lead to acid rain, and explain how this problem can be reduced ?
Sulfur dioxide and Nitrogen dioxide escape into the atmosphere. Calcium oxide can be used to remove Sulfur dioxide from the power station flue gases. Catalytic converters can remove Nitrogen dioxide and Sulfur dioxide from vehicles.
143
Describe two types of measures that the government can put in place to try and reduce pollution ?
- Encourage people to try and change their behaviour
- Governments can change laws to reduce pollution
144
What does renewable mean ?
It won't run out
145
What does non-renewable mean ?
It will run out / finite resource
146
What are example of renewable fuels ?
Wind
Solar
Wave power
147
What are positives of using renewable
fuels ?
They are also carbon neutral, so they don't add greenhouse gases (or other pollutants) to the atmosphere.
(However, CO2, will still be given out during the manufacture of solar panels, wind turbines etc.)
148
What are the negatives for using renewable fuels ?
- They are not reliable
- It takes a lot of wind turbines, solar panels or wave energy collectors to get a fraction of the energy currently supplied by fossil fuels.
149
What are biofuels made from ?
Living matter over a short period of time
150
What is bioethanol made from ?
The fermentation of sugar from crops
151
What is biodiesel made from ?
Refining renewable fats and oils
152
What is biogas produced from ?
The breakdown of organic waste matter.
153
Why are biofuels carbon neutral ?
They produce CO2 when they are burnt, but its CO2 that the plants absorb when they are growing.
(However CO2 is still given out while refining and transporting the fuel, as well as making fertilisers and powering agricultural machinery used to grow and harvest the crops)
154
What else can biodiesel and biogas also be made from ?
Waste that would otherwise go to landfill
155
What is one problem with switching from fossil fuels to biofuels in transports ?
Petrol car engines would have to be modified to use fuels with high ethanol concentrations.
156
What is the problem when you use land to grow crops for fuel ?
The land cannot be used to grow food - this could be a serious problem, as poorer developing countries could use this as a way to make money, and convert farming land to produce crops for fuel, so they may not grow enough food to eat.
157
What can hydrogen gas be burned in ?
They can be burned in a modified engine, or used in a fuel cell. (A fuel cell converts hydrogen and oxygen into water - and this produces electricity ).
158
What is an advantage of using hydrogen
gas ?
Water is the only waste product
159
Can hydrogen be obtained from seawater ?
Yes, but it takes energy to extract it. This is why it is more accurate to think of hydrogen as an 'energy carrier' rather than a true 'energy source'.
160
Why is hydrogen difficult to transport and store ?
It is highly flammable and has to be liquified due to the low energy to volume ratio of hydrogen gas.
161
Why are the demands of energy increasing ?
The world population is growing and countries are becoming richer.
162
To ensure 'energy security', the UK must make sure that it will be able to get enough clean, affordable energy, despite ?
- Increasing competition from other countries for the availability of supplies, which means higher prices.
- Supplies potentially being disrupted due to variou political issues.
163
What does the UK governments plan to ensure energy security involve ?
- Encouraging the public and industry to become more energy efficient.
- Continuing to make use of coal, oil and gas reserves.
-Creating financial incentives to reduce CO2 emissions.
- Using more renewable energy
- Encouraging research of new energy sources.
164
What is it meant by a renewable fuel ?
It won't run out
165
Describe how biodiesel is made ?
By refining renewable fats and oils like vegetable oils.
166
Explain why hydrogen from seawater is more of an 'energy carrier' than a true 'energy source' ?
Hydrogen can be obtained from seawater - but it takes energy to extract it.
167
Describe some of the factors that have to be considered when making a policy to ensure 'energy security' ?
- Using more renewable energy
- Encouraging the public and industry to become more energy efficient.
- Continuing to make use of our coal, oil and gas reserves.
- Creating financial incentives to reduce CO2 emissions
- Encouraging research of new energy sources,
168
Describe two disadvantages associated with the continued large-scale use of fossil fuels as an energy source ?
Continued uses of fossil fuels leads to an increase of carbon dioxide being emitted into the atmosphere, which could lead to problems with climate change.
Fossil fuels are also non-renewable, and so they will eventually run out, leading to problems if we do not find an alternative.
169
Give two reasons why the demand for energy is rising ?
- The worlds population is rising, so more people are demanding energy.
- Countries are getting richer, meaning their industry is growing and more energy - consuming products are being bought.
170
Describe one advantage and one disadvantage of the following fuel alternatives:
a) wind power
b) hydrogen
a) + Does not emit Carbon dioxide into the atmosphere.
- It is not reliable, it is not always windy
b) + Water is the only waste product
- Cannot transport or store hydrogen easily because it is highly flammable.
171
In a classroom debate on the future of fuels, Martin argues that bioethanol is not a solution to the Earth;s 'greenhouse effect' problem because "the combustion of bioethanol still produces carbon dioxide". However, Samantha maintains that bioethanol is "carbon neutral".
To what extent are Martin and Samantha's arguments right or wrong ?
Burning biofuels does produce CO2, however this CO2 is absorbed by crops while they are growing, these crops are used to make biofuels. So this is considered carbon neutral. However, CO2 is still emitted while refining and transporting the fuel, so the overall production is not carbon neutral.
