During the late carbon-burning phase of a massive star, two carbon-12 nuclei can undergo fusion to form a magnesium-24 nucleus. The nuclear equation representing this process is:
612C+612C→1224Mg ^{12}_{6}\text{C} + ^{12}_{6}\text{C} \rightarrow ^{24}_{12}\text{Mg} 612C+612C→1224MgData for these nuclei are given in the table below:
| Nucleus | Mass / u |
|---|---|
| 612C^{12}_{6}\text{C}612C | 12.0000012.0000012.00000 |
| 1224Mg^{24}_{12}\text{Mg}1224Mg | 23.9850423.9850423.98504 |
Constants:
Calculate, in J, the energy released when this reaction occurs.
In one stellar astrophysics model, fusion is assumed to occur once the two carbon nuclei come into contact. Initially, the two nuclei are separated by a very large distance where their mutual electrostatic repulsion is negligible. They are projected towards one another until they fuse. At the moment of fusion, their centres are separated by a distance of 5.8×10−15 m5.8 \times 10^{-15}\text{ m}5.8×10−15 m.
Calculate the total change in electrostatic potential energy, in J, between their initial and final states.
128 exam-style questions on AQA A Level Physics Radioactivity (A-level only), covering Rutherford scattering (A-level only), $\alpha$ , $\beta$ and $\gamma$ radiation (A-level only), Radioactive decay (A-level only), Nuclear instability (A-level only), Nuclear radius (A-level only), Mass and energy (A-level only), Induced fission (A-level only), and Safety aspects (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.