In reply to SHIRAKAWA Akira's message of Wed, 13 Apr 2011 23:12:59 +0200: Hi, [snip] >The question is; how can the 6.15MeV mass-energy increase of >62Ni+p->63Cu account for a total binding energy increase of 8.7MeV, and >yet also be exothermic?
The difference in *total* binding energy is 6.12 MeV, and this is precisely the definition of the energy release when a proton is added to Ni62 to get Cu63, because binding energy is calculated based upon the creation of a nucleus from free particles, and a proton is a free particle (i.e. has zero binding energy). IOW if you calculate the energy released, based upon mass difference, you get 6.12 MeV for the reaction, as expected. The per nucleon binding energy for Cu63 is actually a little less than for Ni62, nevertheless, the additional nucleon more than makes up for this in the total, ensuring that the total for Cu63 is larger than for Ni62. The questioner actually has it backwards. Addition of a proton yields about 8.7 MeV of binding energy, but about 2.6 MeV of this is lost due to the decrease in per nucleon binding energy for Cu63 compared to Ni58, thus of the additional 8.7 MeV, only 6.12 MeV is left over as exothermal energy. Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/Project.html
