L'une des réactions traduisant la fission de l'uranium-235...

L'une des réactions traduisant la fission de l'uranium-235 est :
$$
{ }^{235} \mathrm{U}+\mathrm{n}={ }^{95} \mathrm{Y}+{ }^{139} \mathrm{I}+2 \mathrm{n}
$$

Quelle est l'énergie libérée par la fission selon cette équation stæchiométrique de $1 \mathrm{~g}$ d'uranium-235 ?

Key Concepts

Nuclear Fission

Nuclear fission is the process in which a heavy atomic nucleus splits into two or more smaller nuclei, along with the release of neutrons and a substantial amount of energy. This conversion of nuclear mass into energy underlies the operation of nuclear reactors and atomic bombs, where the splitting of nuclei, like that of uranium-235, changes the binding energy of the system and liberates energy according to Einstein’s mass–energy equivalence principle.

Mass–Energy Equivalence

Mass–energy equivalence is the principle described by Einstein’s equation E = mc², which expresses that mass can be converted into energy and vice versa. In nuclear reactions, the tiny difference in mass (mass defect) between the reactants and products is transformed into a considerable amount of energy, making this concept fundamental for calculating the energy release in processes like fission.

Stoichiometry in Nuclear Reactions

Stoichiometry in nuclear reactions involves the quantitative analysis of the relationship between the amounts of reactants and products in the reaction. For nuclear fission, this means using the balanced nuclear equation to determine the number of fission events and the resultant energy release per unit of fissile material, enabling calculations of energy output from a given mass of nuclear fuel.

Unit Conversions in Nuclear Calculations

Unit conversions play a crucial role in nuclear physics, especially when converting between atomic mass units (amu) and energy units such as mega electron volts (MeV) or Joules. These conversions are necessary to accurately translate the mass defect observed in fission reactions into the energy liberated, making them essential for understanding and computing the energy yield from nuclear reactions.

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