Nuclear fusion
2 marks · NormalThe table shows the mass of particles before and after a nuclear fusion reaction:
| Particles | Total mass (u) |
|---|---|
| Before: deuterium + tritium | 5.031 |
| After: helium + neutron | 5.019 |
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The mass after the reaction is less, and the difference in mass has been converted into energy released in the reaction.
Also accept: energy released due to mass converted to energy
Common mistakes: failing to state energy is released; just stating energy is lost rather than mass is converted
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Marking points
B1 · 1 mark · States that mass is lost (products have less mass than reactants).
B2 · 1 mark · Links the lost mass to energy release (E = mc² idea).
Worked solution
The total mass after the fusion reaction is less than before the reaction. The missing mass has been converted into energy, which is released during the fusion process.