Option C

Option C : Energy


Energy was one of the old SL Applied Chemistry options. When Applied Chemistry became subsumed into Chemistry it became Fuels and Energy and then completely disappeared as an option for the 2007 programme (last exams in November 2015). It has now returned as Option C. My own highly subjective viewpoint (arrived at after writing the Study Guide, this website and some of the examination questions) is that it is perhaps now the easiest of the four options. At this level it deals with some relatively straightforward chemistry some of which, such as crude oil fractions etc., may already have been covered in pre-IB courses. Nevertheless it 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

Option C contains some new material compared to the old Fuels and Energy option, such as 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. New material in the three AHL sub-topics includes 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 new programme.

There is the opportunity to carry out plenty of good practical work (e.g. cracking an alkane, making ethanol by fermenting glucose followed by fractional distillation and making biodiesel by transesterification etc.) although none of it is mandatory. You could also consider taking your students to visit a nearby power station.


The linked pages basically follow the syllabus and take each sub-topic in turn. They start with ‘Pause for thought’, which aims to stimulate and get you (and your students) thinking about some aspect of the topic. A box follows this on how Nature of Science is addressed by the sub-topic, then learning outcomes (‘understandings’ and ‘applications and skills’), clarifications, the international-dimension, teaching tips, key vocabulary and other resources (including videos and the relevant pages in my Study Guide) and suggestions for homework. Each sub-topic has an embedded slide gallery which covers all the syllabus content and contains tasks with worked answers. For all of the topics there is an attached link leading to a separate page with original questions (together with worked answers) on the topic. Although the IB does not test the options using multiple choice questions I have also provided a quiz containing ten questions with the answers explained for each sub-topic as it provides an efficient and quick way for students to test both their knowledge and understanding.

Introductory video

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

  The future of energy

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