Quantitative Analysis of Nuclear Reactions – Practice
Questions:
1) In the net reaction for the CNO cycle, 4 protons fuse to form at He-4 nucleus with an atomic mass of 4.0026u.
a) Determine the mass deficit.
b) Determine the total energy released in MeV.
2) Americium-241 is commonly used in smoke detectors. It supplies the alpha radiation that is used to test for the presence of smoke.
a) Present the nuclear equation for this reaction.
b) Explain why the alpha particle is emitted with much greater kinetic energy than the decayed nuclei.
c) Am-241 has an atomic mass of 241.0568u and an alpha particle has a mass of 4.0026. During the decay, 5.486 MeV of energy is released. What is the mass of the decayed nuclei in atomic mass units?
3. Plutonium-239 can undergo spontaneous fission, forming palladium-112 and cadmium-124, and releasing 3 neutrons. Consider the masses in the table below, and determine the energy released in this reaction in MeV.
| Particle | Mass (u) |
| Neutron | 1.0087 |
| Pd-112 | 111.9073 |
| Cd-124 | 123.9176 |
| Pu-239 | 239.533 |
4. Radium-226 undergoes alpha decay to form Radon-222. The kinetic energy of the decayed Rn-222 nucleus is 3 x 10-14 J following the nuclear reaction. Use the table below to determine the kinetic energy of the alpha particle.
| Particle | Mass (u) |
| He-4 | 4.0026 |
| Rn-222 | 222.0176 |
| Ra-226 | 226.0254 |
Quick Answers:
1a) 4.37 x 10-29 kg b) 24.5 MeV
2a) Am-241 → Np-237 + He-4 b) The Law of Conservation of Momentum dictates that momentum in a closed system must be conserved. Should both particles have the same momentum following the decay, the larger mass of the neptunium nuclei will mean that is will have a much lower velocity than the relatively small alpha particle. c) 237.04832 u
3) 636 MeV
4) 7.47 x 10-13 J
Worked Answers: