Question

Consider a fission reaction where a Uranium-235 nucleus absorbs a neutron and then splits to Strontium, Xenon, and some neutrons. If the strontium nucleus has a mass number of 93 and the Xenon nucleus has a mass number of 140, how much energy is released in a single reaction? Use the attached table for the atomic masses of the nuclei. Give your answer in MeV and with 4 significant figures.

Neutron 0 1 1.008665

Uranium 92 235 235.043923

Strontium 38 87 86.908877 88 87.905612 89 88.907451 90 89.907738 91 90.910203 92 91.911038 93 92.914026 94 93.915361 95 94.919359 96 95.921697 97 96.926153 98 97.928453 99 98.933240

Xenon 54 133 132.905910 134 133.905395 135 134.907227 136 135.907219 137 136.911562 138 137.913950 139 138.918793 140 139.921640 141 140.926650 142 141.929710 143 142.935110 144 143.938510 145 144.944070 146 145.947750

From: G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729: 3–128.

Answer 1

fission reaction. 235 - 93 srt xe + energy & 140 Given atomic masses m (2350) = 235.04 39 m e 935.) - 93.9153 v. m (140xe) = 140.92660 The products have a total mass of Products - 93.91530+ 190-92660 - 234.8419 0 The mass lost is the mass of 235 U EES minus products om - 235.04390- 234.8419 - 0.202 the energy released is E = come so - 10.2020) (331.5MeV/ (~) cr = 188.163 Men

A number of important things arise in this example. The energy released 188.163 is large, but a little less than the earlier estimated 240 MeV. This is because this fission reaction produces neutrons and does not split the nucleus into two equal parts

Most fission produces neutrons, although the number varies with each fission. This is an extremely important aspect of fission, because neutrons can induce more fission, enabling self-sustaining chain reactions.