Option F : Fuels and Energy - notes by Carolina Biasoli

The developments of human society has been directly related to the ability to use and manipulate fuels for energy production. This option considers the chemical principles and environmental issues associated with the use of fossil fuels, and nuclear and solar energy.

F.1         Energy Sources (1 h)

F.1.1     State desirable characteristics of energy sources.
                    These include energy released at reasonable rates (neither too fast nor too slow) and minimal pollution.

F.1.2     Outline current and potential energy sources.
                    Consider fossil fuels, nuclear (fission and fusion), electrochemical cells, solar energy and alternative sources (eg
                    wind, tidal, geothermal).

F.2         Fossil Fuels (4h)

F.2.1      Describe the formation and characteristics of coal, oil and natural gas.

F.2.2     Determine and compare the enthalpies of combustion of coal, oil and natural gas.
                    Calculations could be made using enthalpies of formation or from experimental data. Cross reference with 15.1.

F.2.3     Outline the composition and characteristics of the crude oil fractions used for fuel.
                    Students should have general, rather than specific, knowledge about the types of compounds found in each
                    fraction, the boiling point range and the uses of the fractions.

F.2.4     Describe how the components of a hydrocarbon fuel relate to its octane rating.
                    Octane rating is a measure of the ability of a fuel to resist 'knocking' when burnt in a standard test engine. A fuel is
                    rated relative to heptane (rating of 0) and 2,2,4-trimehylpentane (rating of 100). The role of lead additives in fuels
                    and the role of aromatic compounds in unleaded fuels should be mentioned.

F.2.5     Explain the processes of coal gasification and liquification.
                    Gasification produces synthesis gas and liquification produces liquid hydrocarbons. Relevant equations should be
                    used. Advantages include the elimination of SO2 pollution and the ease of transportation. The main disadvantage
                    is the energy cost of the processes.

F.2.6     Describe how the burning of fossil fuels produces pollutants.
                    The primary pollutants are CO, CO2, SO2, NOx, particulates (fly ash) and hydrocarbons.

F.2.7     Discuss the advantages and disadvantages of the different fossil fuels.
                    Consider the cost of production and availability (reserves) as well as pollution.

F.3         Nuclear Energy (4h)

F.3.1     Distinguish between nuclear reactions and chemical reactions.
                    Emphasize that in nuclear reactions nuclei are converted to other nuclei, while in chemical reactions only valence
                    electrons are involved and atoms do not change into other atoms.

F.3.2     Write balanced nuclear equations.
                    Both the atomic number and mass number must be balanced.

F.3.3     Describe the nature of a , b and g radiation.
                    Compare the charge, mass, penetrating power and behaviour in an electric field.

F.3.4     State the concept of half-life.
                    Half-life is independent of the amount of a radioactive sample.

F.3.5     Apply the concept of half-life in calculations.
                    Restrict this to whole number of half-lives.

F.3.6     Compare nuclear fission and nuclear fusion.

F.3.7     Explain the functions of the main components of a nuclear power plant.
                    Include the fuel, moderator, control rods, coolant and shielding. The materials used for the different components
                    should be considered.

F.3.8     Discuss the differences between conventional power generation and nuclear reactors.

F.3.9     Discuss the concerns about safety in nuclear power plants.
                    Consider the effects of :

  •                     escape of radioactive materials at various stages
  •                     radioactive contamination of ordinary materials
  •                     escape of sodium from a breeder reactor
  •                     loss of control of a nuclear reaction
  •                     nuclear waste

    F.4         Solar Energy (3h)

    F.4.1     State how solar energy can be converted to other forms of energy.
                        Include chemical energy (biomass), thermal energy (passive and active methods) and electricity generation (direct
                        and indirect methods).

    F.4.2     Describe the role of photosynthesis in converting solar energy to other forms of energy.
                        Products of photosynthesis are used for food, primary fuels and conversion to other fuels, eg. ethanol. The
                        equation for photosynthesis is required.

    F.4.3     Discuss how biomass can be converted to energy.
                Include :

  •         direct combustion
  •         combustion of waste materials from other processes
  •         production of biogas
  •         production and use of ethanol

  •             Mention the advantages and disadvantages of each method. The equation for the formation of ethanol from glucose is

    F.4.4     Outline the principles of using solar energy for space heating.
                        Example should include storage of heat by water and rocks.

    F.4.5     Discuss the methods for converting solar energy into electricity.
                        Include parabolic mirrors and photovoltaic cells. Consider the advantages and disadvantages of each method.

    F.5         Electrochemical Energy (3h)

    F.5.1     Explain the workings of lead-acid storage batteries and dry cell (zinc-carbon and alkaline) batteries.
                        Include the relevant half-equations.

    F.5.2     Identify the factors that affect the voltage and power available from a battery.
                        Voltage depends primarily on the nature of the materials used while power depends on their quantity.

    F.5.3     Explain how a hydrogen-oxygen fuel cell works.
                        Include the relevant half-equations.

    F.6         Storage of Energy and Limits of Efficiency (1h)

    F.6.1     Discuss the advantages and disadvantages of energy storage schemes.
                    Include both pumped storage and conversion to hydrogen.

    F.7         Nuclear Stability (2h)

    F.7.1     Predict nuclear stability and mode of decay from neutron to proton ratios.
                    Students should be familiar with the belt of stability in the graph of number of neutrons against number of protons for
                    various stable nuclei.

    F.7.2     Calculate the energy released in a nuclear reaction.

    F.7.3     Define and determine mass defect and nuclear binding energy.
                    Nuclear binding energy is a quantitative measure of nuclear stability. The graph of nuclear binding energy per nucleon
                    against mass number should be used to explain why the products are more stable than the reactants in both nuclear
                    fission and nuclear fusion, and consequently why both processes are exothermic.

    F.8         Radioactive Decay (2h)

    F.8.1     Calculate the change in activity over a period of time.
                    See the data booklet for the integrated form of the rate equation.

    F.8.2     Describe the different types of nuclear waste, their characteristics and their sources.

    F.8.3     Compare the storage and disposal methods for different types of nuclear waste.

    F.9         Photovoltaics (2h)

    F.9.1     State that silicon and germanium are semiconductors.

    F.9.2     Compare the electrical conductivity of a semiconductor with the conductivity of metals and non-metals.
                        Relate this to the ionization energies of semiconductors compared to metals and non-metals.

    F.9.3     Explain the doping of silicon to produce n-type and p-type semiconductors.
                        In p-type semiconductors, electron holes in the crystal are created by introducing a small percentage of a group 3
                        element (eg In, Ga). In n-type semiconductors inclusion of a group 5 elements (eg As) provides extra electrons.

    F.9.4     Describe how sunlight interacts with semiconductors.
                        Photons interact with crystals to release electrons.

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