In reply to Horace Heffner's message of Fri, 20 Jul 2007 03:58:27 -0800: Hi, [snip] >> bring about the exchange. However slight binding energy differences >> between >> isotopes could easily lead to enrichment over time, especially if >> the binding >> energy of the heavier isotope to the electrode material is slightly >> greater than >> that of the respective lighter isotope. > >This could certainly be true. However, even if true, I still think >the dual (e- and D) fugacity concept has some merit on its own. > >That said, isn't it true though that D makes stronger bonds?
AFAIK, yes (see below), however that's exactly what I said here above. > >"Bonds involving deuterium and tritium are somewhat stronger than the >corresponding bonds in light hydrogen..." > >http://en.wikipedia.org/wiki/Deuterium > >Despite this stronger bond, I think a small amount of pure D20 added >to H2O becomes DHO very fast. If the proton were infinitely massive, then the ionization energy of H would be 13.606 eV. However due to the finite mass of the proton, which results in a "reduced" electron mass, the ionization energy of H is only 13.598 eV. The difference is thus about 7.7 meV (not MeV ;). Because the deuterium nucleus is about twice as heavy as the proton, the electron mass is not reduced as much, and consequently I would expect the ionization energy of deuterium to be closer to the 13.606 eV. That in turn implies that D forms slightly stronger bonds than H. With average thermal energies at room temperature on the order of 25 meV, the difference between the bond energy of D and H is fairly easily overcome (but they are of the same order of magnitude). Perhaps needless to say, the difference in reduced mass of the electron for different isotopes of heavier elements is going to be far smaller than that for hydrogen, so any such chemical effect would also be far smaller in those cases. [snip] Regards, Robin van Spaandonk The shrub is a plant.
