weiming1998
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The famed vinegar+bleach mix-dissolved lead?
Today I tried making some hypochlorous acid out of weak vinegar and Ca(ClO)2. I then tried to toss a chunk of lead and several iron wires in, just to
see what happens. I then heat the thing up. The iron wire begin to rapidly accumulate what I would only describe as red rust, but is slimy, won't go
off glassware, and stained my hand when I tried to scrub it with my fingers. But the interesting thing was, the lead started to bubble rapidly! So,
before the solution could get so much lead that I can't pour it down the drain, I prepared another solution and this time, I'm going to put only
lead in there. After heating, the lead did rapidly corrode, producing a brown-black insoluble powder, which I suspect to be lead dioxide. So, my
question is, are the lead hypochlorite still in solution? If it isn't, how did it decompose into lead dioxide instead of lead chloride?
Questions aside, this also proves that the bleach+vinegar mix has at least some use.
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bbartlog
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Lead hypochlorite is unstable (exists only in solution). I expect your precipitate is a mixture of PbO2 and Pb3O4. Whether you have much lead(II)
acetate still in solution, I have no idea.
The less you bet, the more you lose when you win.
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weiming1998
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Looks like I found a source
http://bcs.whfreeman.com/WebPub/Chemistry/ichem5e/Videos/Hyp...
In this source, it says that lead hypochlorite is insoluble in water, and it decomposes to PbO2, the colour of which are exactly like my precipitate.
I guess mystery solved!
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Lithium
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that's brilliant!
i have been leaving 1 kilo of lead in 2 litres of vinegar for 3 months, and you tell me this now!
the lead still has not dissolved!
do you think this would work with other non-reactive metals, say copper or silver?
Li
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weiming1998
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Quote: Originally posted by Lithium  | that's brilliant!
i have been leaving 1 kilo of lead in 2 litres of vinegar for 3 months, and you tell me this now!
the lead still has not dissolved!
do you think this would work with other non-reactive metals, say copper or silver?
Li
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Copper will probably work, as HClO is an oxidizing acid, and it will produce probably copper oxides, but I doubt silver will. If you want soluble
silver salts, use nitric acid, or if you don't have good-quality nitric acid, mix oxalic acid with CaCl2, filter, then dissolve a nitrate salt in the
solution. Bad quality aqua regia, still works wonders on most things. Silver should be no exception. After dissolution, precipitate with Na2CO3. You
get a fine powder of Ag2CO3 that you can filter, collect and make other silver salts.
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woelen
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Silver has the added complication that insoluble AgCl is formed and this may block further oxidation of the underlying silver.
Hypochlorite otherwise is capable of dissolving many many metals at acceptable rate, even more so when heated. In this way I was able even to dissolve
ruthenium metal, by just adding this metal to some bleach with a little added NaOH to make it more alkaline. All other aqueous methods (including
conc. nitric acid, aqua regia and 20% chloric acid) failed.
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LanthanumK
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| Quote: Originally posted by Lithium | that's brilliant!
i have been leaving 1 kilo of lead in 2 litres of vinegar for 3 months, and you tell me this now!
the lead still has not dissolved!
do you think this would work with other non-reactive metals, say copper or silver?
Li
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Add some hydrogen peroxide if you want lead acetate. That dissolution is moderately rapid.
hibernating...
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AJKOER
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I have dissolved Sterling Silver (Ag/Cu) in Vinegar and dilute H2O2. In a few days, you will have a solution of Silver acetate in vinegar. Add a
little base and a precipitate resembling white cottage cheese falls out of solution as Silver acetate is not very soluble in a neutral solution.
Warning, if you think you will just clean the Sterling Silver, do not leave in the Vinegar/H2O2 for more than a few days as noticeable pits will
develop. Actually, this appears not to be a good way to "clean" Sterling Silver at all.
---------------------------------
With respect to Lead (II) hypochlorite, I have an interesting idea. If one wanted to concentrate NaClO, then use it to form a Pb(ClO)2 precipitate.
Separate and react the Pb(ClO)2 with NaOH to obtain a more concentrated NaClO. One source notes that Pb(ClO)2 ignites H2S on contact (see
"Bretherick's handbook of reactive chemical hazards", edited by P. G. Urben, page 1483, link: http://books.google.com/books?ei=95FwT5-rL4Xu0gH3sIj8Bg&... ), which suggests that the salt is stable enough to further react. Note,
concentrating by heating NaClO does not work due to a disproportionation reaction into chloride/chlorate.
[Edited on 27-3-2012 by AJKOER]
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Poppy
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Try to activate your lead:
Melt it in a large spoon and rapidly pour out in fresh water. The lead will acquire a fibrous shape which works best for dissolving purposes
increasing the atack rates up to 100 times or maybe more.
[Edited on 3-26-2012 by Poppy]
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chemicalmixer
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I wonder how a mixture of equal volumes of both 5.25% NaClO and 5% CH3COOH would perform at dissolving most metals, when compared with a solution
which uses equal volumes of both 3% H2O2 and 5% CH3COOH instead.
Seems that the bleach/vinegar mix would likely dissolve metals more vigorously, whereas a peroxide/vinegar solution would be advantageous for
dissolving metals such as silver and lead, which tend to form insoluble chloride salts (not to mention there'd less nasty fumes).
Would it be helpful to first chill the bleach and vinegar before mixing them, in order to avoid losing Cl2, and also to cut down on the evolution of
fumes?
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LanthanumK
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Bleach/vinegar is also more problematic in that there is left over NaCl in the solution, making the resulting metal salt quite impure when evaporated.
Hydrogen peroxide decomposes to water easily, and excess acetic acid can be remedied by adding an excess of metal and hydrogen peroxide to remove the
HAc.
hibernating...
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chemicalmixer
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I found an amateur experimenter's video which shows how iron oxide (for thermite) can be made from water, steel wool, bleach, and vinegar:
https://www.youtube.com/watch?v=z06nSMiICcI
AFAIK, common steel wool also contains a bit of chromium, not to mention the steel wool likely has a thin layer of oil to prevent it from rusting on
the store shelves.
As an improvement to this young lad's method, perhaps he could have first soaked the steel wool in acetone or naptha, and then decanted the dirty
solvent before allowing the remaining solvent to evaporate from the now clean steel wool. This would remove any machine oil, thusly avoiding the
creation of chlorinated by-products, as well as speeding up the reaction rate. Secondly, instead of diluting the reactants - with tap water of all
things - he might have instead used an undiluted mixture of bleach and white vinegar, after first pre-chilling the two components before mixing them,
and then loosely capping the jar, in order to avoid pressure buildup of Cl2 gas. Finally, the unreacted steel wool could be filtered, and then the
iron precipitated from the solution by adding a solution of NaOH, Na2CO3, or NaHCO3, then saving the filtrant. If a carbonate salt was used, the iron
carbonate, i assume, would then need to be calcined to form iron oxide. If NaOH was used in excess, the chromium, which is amphoteric, could be
readily removed from the iron.
[Edited on 27-3-2012 by chemicalmixer]
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AJKOER
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I think it is worth mentioning that an active part of the bleach and vinegar is not just HOCl via:
NaClO + HAc --> HOCl + NaAc
but apparently also the Sodium acetate which has been described as a catalyst. My view on the reaction of HOCl and Fe is temporary formation of
Fe(ClO)2, which decomposes forming FeCl3 and liberating some Cl2. Normally, absent the Sodium acetate (NaAc), the FeCl3 in a few days undergoes a
hydrolysis forming a residue of Fe2O3. One can verify this by using a dilute solution of H2SO4 (or NaHSO4 or even H2CO3) in place of the Acetic acid.
However, in the presence of NaAc, the solution remains stable (possibly transforming into Ferric acetate).
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woelen
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Probably the acetate works as a coordinating agent. The presence of coordinating agents can strongly alter the redox potential for oxidation of many
metals. A well known example is that gold quite easily dissolves in a cyanide solution, through which some air is bubbled. The oxygen then oxidizes
the gold and subsequently the gold goes in solution as a cyanide complex.
It is known that ferric ions coordinate to acetate ions quite well, forming a deep red/brown complex. It might be that this reaction makes the
oxidation of the iron more likely to occur.
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