Option C : Energy

Introduction to C.1 to C.5 and C.6 to C.8

This option contains material that is important and relevant to the modern era and to the successful functioning of society and to the global environment.

Image from Future Energy Solutions

It considers the importance of comparing the energy density and the specific energy of different fuels, the efficiency of an energy transfer and the calculation of carbon footprints. The core covers fossils fuels, nuclear fission and fusion and solar energy as well as the environmental impact, specifically global warming. The three AHL sub-topics include microbial fuels cells, the Nernst equation and dye-sensitized solar cells. Like all the options it contains the four common strands of quantitative, analytical, environmental and organic chemistry. The analytical is covered in the core by the use of absorption spectroscopy to help determine the composition of stars and both visible spectroscopy (why chlorophyll and related compounds are coloured) and infrared spectroscopy (greenhouse gases) are mentioned. Considering the importance attached to replacing fossil fuels with cleaner alternative forms of energy it seems a little strange that the core sub-topic C.4 Solar energy is confined just to biomass and makes no mention of energy sources normally covered under solar energy such as passive solar heating and photovoltaic cells etc. In 2015 the price of oil fell considerably. One of the reasons for this is the increasing use of hydraulic fracturing (known as 'fracking'), although the oil price is recovering now. Fracking is controversial and could provide an excellent example to bring in the Nature of Science and Theory of Knowledge as well as cover some good chemistry so it seems surprising to me that 'fracking' is not mentioned specifically in the current programme.

Introductory video

A really good video by Cambridge University on the future of energy to introduce this Option and to get you thinking.

  The future of energy

Associated pages

C.1 Energy sources

After studying this topic you should be able to determine the energy density and specific energy of a fuel from the enthalpies of combustion, densities and the molar mass of the fuel...

C.2 Fossil fuels

After studying this topic you should be able to discuss the cracking and reforming reactions of hydrocarbons and explain how the octane number is improved through these processes...

C.3 Nuclear fusion & nuclear fission reactions

After studying this topic you should be able to construct equations for nuclear fusion and fission reactions and explain nuclear reactions in terms of the binding energy per nucleon...

C.4 Solar energy

After studying this topic you should be able to identify features of molecules that allow them to absorb visible light and explain the reduced viscosity of esters produced with methanol and ethanol...

C.5 Environmental impact - global warming

After studying this topic you should be able to explain the molecular mechanisms by which greenhouse gases absorb infrared radiation and discuss the evidence for the relationship between the increased concentration of greenhouse gases and global warming..

C.6 Electrochemistry, rechargeable batteries & fuel cells

After studying this topic you should be able to distinguish between fuel cells and primary cells and deduce the half equations for the electrode reactions in a fuel cell...

C.7 Nuclear fusion & fission (HL)

After studying this topic you should be able to calculate the mass defect and binding energy of a nucleus and apply Einstein’s equation E = mc2, to determine the energy produced in a nuclear reaction...

C.8 Photovoltaic cells and DSSCs

After studying this topic you should be able to relate the degree of conjugation in the molecular structure to the wavelength of the light absorbed and explain the operation of photovoltaic and dye-sensitized solar cells...

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