In reply to Jones Beene's message of Mon, 29 Jul 2013 06:21:43 -0700: Hi Jones,
Where they talk about endothermic reactions, they are talking about fusion of an element with itself, not with Hydrogen. This is because in stars, by the time the mid-level elements are formed, the Hydrogen *in the core* has long been consumed so there is none left to fuse with the other elements. Because the binding energy is at a peak around Fe/Ni, any further fusion (e.g. Ni + Ni) would be endothermic. However fusion of *Hydrogen* with any of them would still be exothermic (as already shown here below). While the height of the Coulomb barrier plays a role in the likelihood that a fusion reaction between e.g. Ni & H will occur, such reactions are not energetically forbidden, i.e. they are exothermic, not endothermic. >Hi Robin, > >None of those reactions are net exothermic. > >You failed to include the energy necessary to overcome the Coulomb barrier, >which was the gist of the original message. > >In all cases that high level of threshold energy, which must be expended, is >greater than the yield. Tunneling does not change that situation because >tunneling itself is conservative. > >This should be obvious - depending on how a google search is worded you will >get about 10 million hits for something like.... > >"Fusion of elements with mass numbers (the number of protons and neutrons) >greater than 26 uses up more energy than is produced by the reaction. Thus, >elements heavier than iron cannot be fuel sources in stars." > > > >-----Original Message----- >From: mix...@bigpond.com > >In reply to Jones Beene's message of > > >Hi, > >>Proton capture is net endothermic >>with nickel and leads to significant radioactivity. > >1H+58Ni => 59Cu + 3.419 MeV > >1H+60Ni => 61Cu + 4.801 MeV > >1H+61Ni => 62Cu + 5.866 MeV >1H+61Ni => 58Co + 4He + 0.489 MeV > >1H+62Ni => 63Cu + 6.122 MeV >1H+62Ni => 59Co + 4He + 0.346 MeV > >1H+64Ni => 65Cu + 7.453 MeV >1H+64Ni => 61Co + 4He + 0.663 MeV > >All these reactions are exothermic. > >Regards, > >Robin van Spaandonk > >http://rvanspaa.freehostia.com/project.html > > Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html
