Autodissociation of tritiated water

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Auto-dissociation of tritiated water
Maria A. Gomez, Laura Fernandez 08, Lindiwe
Ndebele 08 Mount Holyoke College
Slightly preferred at 60C
B3LYP/6-311(2d,p) is used to find the optimum
energy of each species along with solvating
waters. Quasi-chemical analysis is used to find
the most probable solvated species. With this
analysis, pKw for each possible HTO dissociation
and H2O dissociation is 17 at 25C. At 60C, the
pKw for H2O dissociation shifts to 15 and 12
using harmonic and anharmonic approximations.
The direction of this shift is consistent with
experiment. Further, dissociation of tritiated
water into HO- and T species seems to be
preferred at higher temperatures in agreement
with experiment. As the temperature increases,
the most probable solvating number of waters for
hydroxide appears to shift from 3 to 2.