How do I find the energy released by uranium fission into Nb and Pr ? Every time I see the equation for some nuclear fission it always just states the energy released but what if we didn't know it as a broader question the elements used before are just an example of a fission equation I saw.

  • 1
    $\begingroup$ Well, you could compare the binding energies of the parent and daughter nuclei. $\endgroup$
    – Jon Custer
    Feb 4, 2016 at 0:42
  • $\begingroup$ so sum the Nb and Pr for example and find the difference ? $\endgroup$
    – darren
    Feb 4, 2016 at 0:46
  • $\begingroup$ Nb and Pr cannot be the fission products as the sum of their atomic numbers is 100, not 92. Protons aren't destroyed in fission reactions. In any case, for such a calculation you need to fully specify the fission isotopes (as well as the starting U isotope). $\endgroup$
    – Gert
    Feb 4, 2016 at 1:03
  • $\begingroup$ Nb and Pr may result from different uranium fissions chains $\endgroup$
    – user46925
    Feb 4, 2016 at 1:38
  • $\begingroup$ @igael - the poster obviously believes otherwise. $\endgroup$ Feb 4, 2016 at 2:51

2 Answers 2


The sum of the actual atomic masses of the reaction products minus the sum of the actual atomic masses of the reacting species gives you the amount of mass converted to energy during the fission. That latter amount can be found by applying $E=mc^2$ to that mass deficit.

As I wrote in my comment, protons cannot be destroyed in nuclear fission, so the atomic number of the fissile nucleus must match the sum of the atomic number of the fission isotopes.

An example of a real calculation can be found here.


As written upper , Nb and Pr cannot be a pair of fission products . With a correct fission reaction , I can give a complete approximate calculation by hand . At the end , I obtain the energy of each fission product .


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