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Dear CCLs,
I collected thermodynamic data you required. This
new database, "Comprehensive Handbook of Chemical Bond Energies", will
be published by CRC Press 2006.
I would show you the detailed values in advance if
you need some.
Yu-Ran Luo, Ph.D.
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----- Original Message -----
Sent: Thursday, September 08, 2005 2:33
PM
Subject: CCL: need the free energy values
of water species
The recentt discussion of thermodynamic quantities for water,
the proton, etc., in aqueous solution prompts me to offer a caveat to the
experimental numbers that have so far been listed.
Each number that I
have seen from the list thus far has LACKED any specification of standard
state. This is a common flaw in the published literature, too (and a less
understandable one since we are not talking about quick email messages) and
can introduce fairly large errors if thermodynamic cycles are constructed
without careful attention to common standard states.
I and several
coauthors published a paper recently in J. Chem. Ed. discussing the
standard-state issue in some detail, and moreover providing what we consider
to be the best consensus assignment of the free energy of solvation of the
proton (which is equivalent to defining the absolute potential of the normal
hydrogen electrode, incidentally). That reference
is
Lewis, A.; Bumpus, J. A.;
Truhlar, D. G.; Cramer, C. J. "Molecular Modeling of Environmentally Important
Processes: Reduction Potentials" J. Chem. Ed. 2004, 81,
596.
I suspect that it would violate copyright
agreement for me to attach that article to this email, but for those who do
not have access to the journal, I would be happy to reply to personal requests
for reprints (as a pdf). I also note that an erratum has been submitted that
indicates that even after all our efforts, we too made a small standard-state,
ahem..., error. It turns out that we were lucky, because our error was
essentially exactly equal to the difference between the best estimate at the
time and a better estimate that subsequently appeared (so that we regard all
numbers in the published paper to still be correct), but it illustrates just
how tricky the standard-state issue can sometimes be. The erratum has not yet
appeared, and I'd be happy to send a preprint of that, too, but note again
that the bottom line is that the published article contains only correct data
-- the issue is more one of discussion.
Chris Cramer
P.S. In the
1 atm (gas) to 1 M (aq) standard state, the free energy of solvation for the
proton that we recommend is -1096.6 kJ/mol. The two most recent estimates from
simulation and an interpretation of ion-cluster data (for the same standard
state choice) are -1097.9 +/- 4.2 and -1104.5 +/- 8.4 kJ/mol, respectively.
See Tissandier, M. D.; Cowen, K. A.; Feng, W. Y.; Gundlach, E.; Cohen, M. H.;
Earhart,
A. D.; Coe, J. V.; Tuttle, T. R. J. Phys. Chem. A 1998, 102,
7787-7794 and Zhan, C.-G.; Dixon, D. A. J. Phys. Chem. A 2001, 105,
11534-11540.
Sent to CCL by: Laurynas Riauba
[laurynas.Riauba[-]chf.vu.lt]
You can get some numbers at
http://webbook.nist.gov
For liquid water, formation
enthalpy is
-285.84 kJ*mol-1, entropy -69.96 J *mol-1*K-1
In "Smith B.
J.,Calculation of aqueous proton dissociation constants of quinoline and
hydroxyquinolines : A comparison of solvation models, Phys. Chem. Chem.
Phys., 2000, 2, 5383-5388" following values are mentioned (according a
reference, data is from NIST page):
"Experimental values for the
proton enthalpy of formation
(1530 kJ mol~1), entropy (108.95 J mol~1
K~1) and solvation
Gibbs energy (1085.8 kJ mol~1)"
Note: I suppose
solvation Gibbs energy should have negative sign.
For calculations of
solvation energy you can look also at
http://www.chemistry.ohio-state.edu/~coe/Coe_review.pdf
Laurynas
Riauba,
PhD student,
Vilnius University,
Vilnius,
Lithuania
CCL wrote:
Dear all,
I would like to know the experimental values of
free energy of
1. Water
2. Hydronium (H3O+) ion
3. Hydroxide
(OH-) ion
4. Proton (H+)
in gas-phase and condensed phase
(solvate-phase)
If someone know, or the source that I can retrieve
these values,
could you please inform me.
Thank you very much for
your kind consideration.
Best regards,
Pong
Jaturong
jr_pk2001]![yahoo.com
<http://aa.f516.mail.yahoo.com/ym/Compose?To=jr_pk2001]![yahoo.com&YY=74978&order=down&sort=date&pos=0>
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instant messages to your online friends
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--
Christopher
J. Cramer
University of Minnesota
Department of Chemistry
207
Pleasant St. SE
Minneapolis, MN
55455-0431
--------------------------
Phone: (612) 624-0859 || FAX:
(612) 626-2006
Mobile: (952)
297-2575
cramer]![pollux.chem.umn.edu
http://pollux.chem.umn.edu/~cramer
(website
includes information about the textbook "Essentials
of Computational
Chemistry: Theories and Models, 2nd
Edition")
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