Nuclear Reactions: Fission, Fusion, and Chain Reactions
What Are Nuclear Reactions?
Nuclear reactions involve changes in an atom’s nucleus, releasing immense energy due to mass-to-energy conversion (
).
Types of Nuclear Reactions
Nuclear Fission
A heavy nucleus splits into smaller nuclei, releasing energy and neutrons.
Example: Uranium-235 fission in nuclear reactors.
Nuclear Fusion
Light nuclei combine to form a heavier nucleus, releasing energy.
Example: Hydrogen fusion in the Sun.
Chain Reactions
In fission, released neutrons cause further fissions, creating a self-sustaining chain reaction.
Applications of Nuclear Reactions
Energy Production
- Fission powers nuclear reactors.
- Fusion is the focus of experimental reactors like ITER.
Medicine
Radioisotopes from nuclear reactions are used in cancer treatments and diagnostics.
Space Exploration
Radioisotope thermoelectric generators (RTGs) power space probes.
Example Problem
A fission reaction releases 
per nucleus. Calculate the energy released by fissioning 
of Uranium-235.
- Convert Energy to Joules:
![\[ 1 \, \text{MeV} = 1.6 \times 10^{-13} \, \text{J}, \quad 200 \, \text{MeV} = 200 \cdot 1.6 \times 10^{-13} = 3.2 \times 10^{-11} \, \text{J} \]](https://skinattuition.co.uk/core/ql-cache/quicklatex.com-0415affd7080c145e5a0b979123a3cce_l3.png "Rendered by QuickLaTeX.com")
- Number of Nuclei in
:
![\[ \text{Nuclei} = \frac{\text{Avogadro's Number} \cdot \text{Mass}}{\text{Molar Mass}} = \frac{6.02 \times 10^{23} \cdot 1}{235} \approx 2.56 \times 10^{24} \]](https://skinattuition.co.uk/core/ql-cache/quicklatex.com-850d58a1f68b5ebff5b0e40811a0faed_l3.png "Rendered by QuickLaTeX.com")
- Total Energy:
![\[ \text{Energy} = 3.2 \times 10^{-11} \cdot 2.56 \times 10^{24} = 8.2 \times 10^{13} \, \text{J} \]](https://skinattuition.co.uk/core/ql-cache/quicklatex.com-0e042b40c2d0262aa36de63421bf1855_l3.png "Rendered by QuickLaTeX.com")
Practice Questions
- Explain the difference between fission and fusion.
- Calculate the energy released by fusing of deuterium.
- Describe one real-world application of chain reactions in energy production.
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