Dr. Beaker
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electrochemistry of SO2 solutions
I was wondering...
it is known that some sulphites can be solvated in liquid SO2 (b.p -10 C, can be acheived by ice+salt which gives about -12 c) if, say we take Na2SO3
(which is easily made from NaOH and SO2 in water) disolve it in liquid SO2 and electrolize, we might get the following at the anode:
SO3(-2) -> SO3 +2e-
at the cathode I believe we'll get elemental S or lower (?) SOx species like thiosulphate.
some other possibilities:
SO3(-2) + SO3 -> SO4(-2) + SO2 (SO3 is a stronger acid)
2SOx(-2) -> S2O2x(-2) +2e-
SOx(-2) -> SO(x-1) +2e- +O (oxygen in "state of forming")
however, both peroxy anions and atomaric O may oxedize SO2 to SO3.
bottom line, it looks like we just getting the sulphate and not SO3...
what you guys think? comments?
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12AX7
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Lithium batteries work in an SO2 electrolyte, IIRC. Should be able to reverse and obtain reduced metallic cation, no?
Tim
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BromicAcid
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Doing a quick search reveals that the lithium/sulfur dioxide battery is non-rechargeable, there are other lithium battery systems that are though.
Still though, this is fairly off topic and not specifically the subject that Dr. Beaker was attempting to broach (although technically still under the
correct subject heading). Personally I know little about using SO<sub>2</sub> as a non-aqueous solvent for electrolysis beyond the fact
that it is one of the mediums that they first observed carbocations in from certain alkyl halides dissociating and dissolving to make conducting
solutions in it.
SO<sub>2</sub> is somewhat of a polar solvent, being able to dissolve 15 grams of NaI in 100 g liquid sulfur dioxide, so I could see it
being able to dissolve at least noticeable sulfite, but still if you can only pull it down to -12C or so, you're going to have massive vapor pressure,
it will be on the verge of boiling, so I would say you have to go noticeably lower. For the electrolysis aspect. All the potentials are screwy in
non-aqueous mediums, and you're working with salts of an acid of the solvent in question, you don't even know what kind of ions they will decide to
form when they dissolve. So I really wouldn't hazard a guess as to what you would end up with. Never the less liquid sulfur dioxide as a solvent for
electrolysis has been widely investigated in the past and I bet with a little searching you could find a nice juicy book on the subject.
[Edited on 12/5/2005 by BromicAcid]
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