Why energy is released during nuclear fission and fusion?
Answers
Nuclear fusion is the reaction in which two or more nuclei combine together to form a new element with higher atomic number (more protons in the nucleus). The energy released in fusion is related to E = mc2 (Einstein’s famous energy-mass equation). On earth, the most likely fusion reaction is Deuterium-Tritium reaction. Deuterium and Tritium are both isotopes of hydrogen.
21Deuterium + 31Tritium = 42He + 10n + 17.6 MeV
For a nuclear fusion reaction to occur it is necessary to bring two nuclei so close that nuclear forces become active and glue the nuclei together. Nuclear forces are small-distance forces and have to act against the electrostatic forces where positively charged nuclei repel each other. This is the reason why nuclear fusion reactions occur mostly in high density, high temperature environment.
Nuclear fission is the splitting of a massive nucleus into photons in the form of gamma rays, free neutrons, and other subatomic particles. In a typical nuclear reaction involving 235U and a neutron:
23592U + n = 23692U followed by 23692U = 14456Ba + 8936Kr + 3n + 177 MeV
For a fission reaction, two conditions need to be satisfied:
· Critical mass of the substance (the minimum amount of mass is required for fission to be self-sustaining).
· A relatively slow neutron is required to initiate the process.
Answer:
Abundant energy: Fusing atoms together in a controlled way releases nearly four million times more energy than a chemical reaction such as the burning of coal, oil or gas and four times as much as nuclear fission reactions (at equal mass).