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AJKOER
Radically Dubious
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Quote: Originally posted by DraconicAcid  | | Yes, we know that radicals like SO4(-) can react with metals. But that doesn't mean that a reaction with metal signifies the presence of a radical.
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Yes, true in general, but here, we are addressing the interaction of carbonated water, 3% H2O2 (normally stabilized by acid) and a minor amount of sea
salt acting on Al in the presence of Fe in 24 hours.
If there were significant amounts of say aluminum carbonate or basic aluminum carbonate created, possible options for the responsible reagent could be
either the bicarbonate ion (or perhaps the peroxymonocarbonate ion formed from CO2 and H2O2), or the carbonate radical anion. In my opinion, the
better guess would be the highly acidic •CO3- radical anion.
[Edited on 28-9-2018 by AJKOER]
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AJKOER
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Came across a theoretical paper estimating the calculation of pKa from free energy data for the radical RH+• in solution, title: 'Thermochemical
parameters for organic radicals and radical ions. Part 1. The estimation of the pKa of radical cations based on thermochemical calculations' by A.
MARTIN DE P. NICHOLAS and DONALD R. ARNOLD, published in Can. J. Chem. 60, 2165 (1982). Link: http://www.nrcresearchpress.com/doi/pdf/10.1139/v82-310 .
Interestingly, to quote:
"Calculations show that the toluene radical cation is an extremely strong acid and the benzene radical cation a moderately strong acid in acetonitrile
solution."
Also, per Method I of calculating pKa, to quote:
"...the pKa of the radical cation is dependent upon the free energy change DeltaG6 (eq. [6]) and is given by eq. [7].
[7] pKa(RH+•) = DeltaG6/2.303RT "
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AJKOER
Radically Dubious
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Came across another interesting comment at https://digitalcommons.ohsu.edu/cgi/viewcontent.cgi?article=... to quote:
“Hydrogen peroxide is at least present in indoor air, is highly soluble in water, and can reacts with silver surfaces to produce free radical
species [10]:
Ag(s) + H202 = Ag+ + OH- + .OH (15) “
where [10] refers to the article: Graedel T. E., Corrosion mechanisms for silver exposed to the atmosphere, Journal of the Electrochemical Society.
Vol. 139 (7), pp. 1963- 1970, 1992, and the abstract states:
“Gaseous hydrogen peroxide, which is sometimes present, strongly accelerates silver corrosion.”
The above suggests to me a possible microwave assisted dissolution of a piece of Silver metal in a H2O2/NaHSO4 mix in the presence of graphite rods,
which I will do pending acquisition of an appropriate source of Silver.
Some may find this patent reference interesting, https://patents.google.com/patent/EP0711753A1 .
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If one thinks that the Eq (15) above suggests a path to a good disinfectant spray, you are right but a little late, see https://medium.com/@SilverHydrogenPeroxide/silver-hydrogen-p... .
[Edited on 16-12-2018 by AJKOER]
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j_sum1
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Thread Pruned
23-12-2018 at 00:58 |
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