C.3 Nuclear fusion & nuclear fission reactions
Written specifically for students to provide help and support for the IB Diploma chemistry programme this page provides full coverage of the syllabus content of Option C - sub topic C.3. It encourages you to think critically and provides many questions with full worked answers so that you can monitor and improve your knowledge and understanding.
.png)
Learning outcomes
After studying this topic you should be able to:
Understand:
Nuclear fusion
- When light nuclei undergo fusion reactions the binding energy per nucleon is increased.
- Fusion reactions have the potential to be a promising future source of energy as the fuel is abundant, inexpensive and produces no radioactive waste.
- The composition of stars can be analysed from their absorption spectra.
Nuclear fission
- When heavy nuclei undergo fission reactions the binding energy per nucleon is increased.
- 235U undergoes a fission chain reaction:
- The mass of fuel needed for a fusion reaction to be self-sustaining is known as the critical mass.
- 239Pu, which is used as a fuel in breeder reactors, is produced from 238U using neutron capture.
- Radioactive waste may contain radioactive isotopes with short and long half-lives.
- Half-life is the time taken for half a given number of atoms to decay.
Apply your knowledge to:
Nuclear fusion
- Construct equations for nuclear fusion reactions.
- Explain nuclear fusion reactions in terms of the binding energy per nucleon.
- Explain the atomic absorption spectra of hydrogen and helium, including the relationships between the absorption lines and electron transitions.
Nuclear fission
- Deduce equations for nuclear fission reactions.
- Explain nuclear fission reactions in terms of the binding energy per nucleon.
- Discuss the storage and disposal of nuclear waste.
- Solve problems involving radioactive decay.
Relationships & vocabulary
Nature of science
If the widespread use of nuclear fission can be used for energy production in the future, it would lead to a large reduction in greenhouse gas emissions.
The process taking place in the atomic bomb is nuclear fission whereas the process taking place in the hydrogen bomb is nuclear fusion.
International-mindedness
The International Atomic Energy Agency (IAEA). monitors the use of nuclear energy internationally
Research into high energy particle physics involves international collaboration (there are accelerator facilities at CERN, DESY, SLAC, Fermi lab and Brookhaven). The results are disseminated and shared by scientists in many countries.
The International Thermonuclear Experimental Reactor (ITER) project is a collaboration between many countries and aims to demonstrate that fusion is an energy source of the future.
Vocabulary
| fusion | fission | binding energy | critical mass |
| half-life, t½ | low-level nuclear waste (LLW) | high-level nuclear waste (HLW) |
Learning slides
You can use this slide gallery for learning or for reviewing concepts and information. It covers all the key points in the syllabus for this sub-topic.
Nuclear fusion & fission reactions:
Nuclear fusion & fission reactions:
Nuclear fusion & fission reactions:
Nuclear fusion & fission reactions:
Nuclear fusion & fission reactions:
Nuclear fusion & fission reactions:
Nuclear fusion & fission reactions:
Nuclear fusion & fission reactions:
Nuclear fusion & fission reactions:
Nuclear fusion & fission reactions:
Something to think about
The moon - a source of helium-3?
Man first walked on the moon on 20 July 1969 and last set foot on the moon on 14 December 1972. Recently there has been increased interest in returning to the moon and one of the reasons for this is the potential to mine helium-3 as a future source of energy back on Earth.
The first hydrogen bomb tested in 1952 involved the reaction between deuterium and tritium (known as “D-T fusion”).
The syllabus states that, “Fusion reactions are a promising energy source as the fuel is inexpensive and abundant, and no radioactive waste is produced.” About one in every six thousand naturally occurring hydrogen atoms is deuterium so deuterium can be obtained from water. Tritium has to be made by reacting neutrons with lithium-6, but unlike deuterium it is radioactive.
Another reaction that has been used to produce fusion energy is the reaction between two deuterium atoms (“D-D fusion”).
This has the advantage that the fuel is not radioactive but like the D-T fusion it produces energetic neutrons. These make the components of the reactor radioactive so radioactive waste is produced.
A much more promising source of future fusion energy is the reaction of helium-3 with itself. Helium-3 is not radioactive and since no neutrons are produced there is no radioactive waste either.
This reaction has been demonstrated to be feasible and really would be a clean fuel. The problem is that there although helium-3 does occur naturally on Earth as a decay product it is only in very small quantities and it has to be mIB Docs (2) Teamfactured from neutron bombardment. However it is much more prevalent on the moon and it has been estimated that just 25 tonnes of helium-3 could provide enough energy to satisfy all the energy requirements of the US for one year. Hence the renewed interest in lunar exploration.
Test your understanding of this topic
(Note that your teacher may have restricted your access to some or all of these questions and worked answers if they are going to use them as a class test or set them as an assignment.)
For ten 'quiz' questions (for quick testing of knowledge and understanding with the answers explained) see MC test: Nuclear fusion & nuclear fission reactions.
For short-answer questions see Nuclear fusion & nuclear fission questions together with the worked answers on a separate page Nuclear fusion & fission answers.
More resources
1. A simple but useful description of nuclear fission and how it can be controlled in a nuclear power plant by Fuse School- Global Education.
2. A more detailed account of nuclear energy which includes the importance of binding energy from The Science Channel (although note that electron volts (as Mev) is used as the unit for energy).
3. A quick rundown on how to deal with nuclear waste by D News.