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Chemistry Questions
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ghporter
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Jul 6, 2017, 02:25 PM
 
I was speaking with an acquaintance about getting ready to mix up my old reliable swimmer's ear preventive: equal parts alcohol, hydrogen peroxide and white vinegar. He stated that mixing peroxide and vinegar would produce "peracetic acid," and it was nasty and toxic and that I was out of my mind putting anything like that in my ear.

Well peracetic acid is a real thing, and it's apparently quite a bit more active an acid than plain old acetic acid (in vingar). But really, how much of this is going to be produced by mixing equal parts 5% white vinegar and 3% hydrogen peroxide? Chemistry was a long, long time ago, so I'm not sure I could even get close to a real answer any time soon.

And researching peracetic acid got me all sorts of "interesting" information. Such as using 50/50 vinegar and peroxide to clean lead from rifle barrels or silencer parts. This produces lead acetate, which is one of those horribly toxic things that is hard to get rid of safely, let alone legally. It's not just "a thing," but this mixture is considered a tried-and-true way to de-lead firearms parts.

And that lead me to discussions of interesting uses of citric acid. Someone was comparing vinegar to citric acid for cleaning bullets, and things got particularly weird from then on. In one discussion there was an explanation of how different citric and acetic acids were, which was countered by someone posting how horribly bad for you citric acid really is, and that we should avoid citrus like the plague. Good times...

So if anyone has enough current chemistry knowledge, can you give me the details on how "dangerous" (or not!) my swimmer's ear drops are? And while you're at it, because now I'm curious, how does lead (probably as lead oxide) react to acetic acid and to citric acid? I'll appreciate the effort!

Glenn -----OTR/L, MOT, Tx
     
andi*pandi
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Jul 6, 2017, 03:40 PM
 
I'd heard of the alcohol thing before, but not the mix.
     
ghporter  (op)
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Jul 6, 2017, 04:07 PM
 
Plain alcohol just helps dry the ear. Alcohol and peroxide "fizzes" out any growth, like most swimmer's ear issues start with. Adding the vinegar helps prevent such things by making the environment more acid. The mix also helps loosen ear wax, which ain't a bad thing for some people.

Glenn -----OTR/L, MOT, Tx
     
Waragainstsleep
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Jul 6, 2017, 07:54 PM
 
Wikipedia seems to think the vinegar is whats really doing the trick.

https://en.wikipedia.org/wiki/Otitis_externa#Prevention

Read the intro at the top as well, it mentions acetic acid as an antibiotic.
I have plenty of more important things to do, if only I could bring myself to do them....
     
P
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Jul 7, 2017, 05:24 AM
 
Originally Posted by ghporter View Post
I was speaking with an acquaintance about getting ready to mix up my old reliable swimmer's ear preventive: equal parts alcohol, hydrogen peroxide and white vinegar. He stated that mixing peroxide and vinegar would produce "peracetic acid," and it was nasty and toxic and that I was out of my mind putting anything like that in my ear.

Well peracetic acid is a real thing, and it's apparently quite a bit more active an acid than plain old acetic acid (in vingar). But really, how much of this is going to be produced by mixing equal parts 5% white vinegar and 3% hydrogen peroxide? Chemistry was a long, long time ago, so I'm not sure I could even get close to a real answer any time soon.
Depends entirely on how much water there is. I'm not sure if this formula will show up, but see the Wikipedia page if it doesn't. It is the second from the top in the section "Production"

H2O2 + CH3CO2H ⇌ CH3CO3H + H2O

That is an equality reaction (not sure about the english term). Written in generic terms, it is

peroxide + acetic acid ⇌ peracetic acid + water

This means that we will always have all four substances present, just in varying amouints. The amounts can be calculated. If we refer to the concentration of peroxide (in mol/g) as [peroxide], we get an equation like

[peracetic acid]*[water]/([peroxide]*[acetic acid] = K

With K being a constant. This means that if you for instance increase the amount of peroxide in the solution, that will force the reaction to "to the right", and it will create more peracetic acid, consuming peroxide and acetic acid until the equation is in balance again.

With me so far? Now, the important thing is the last term, the concentration of water. If you do all of this highly diluted in water, the concentration of water in the solution will be very high and drive the reaction "to the left", ie prevent the formation of peracetic acid. As long as there is sufficient water present, you don't have to worry about the presence of peracetic acid. If you on the other hand let it dry out, then yes there will be peracetic acid.

I guess the only advice I can give is that if you do this, make sure that the area does not dry out, and flush it with lots of water afterwards.

Originally Posted by ghporter View Post
And researching peracetic acid got me all sorts of "interesting" information. Such as using 50/50 vinegar and peroxide to clean lead from rifle barrels or silencer parts. This produces lead acetate, which is one of those horribly toxic things that is hard to get rid of safely, let alone legally. It's not just "a thing," but this mixture is considered a tried-and-true way to de-lead firearms parts.

And that lead me to discussions of interesting uses of citric acid. Someone was comparing vinegar to citric acid for cleaning bullets, and things got particularly weird from then on. In one discussion there was an explanation of how different citric and acetic acids were, which was countered by someone posting how horribly bad for you citric acid really is, and that we should avoid citrus like the plague. Good times...

So if anyone has enough current chemistry knowledge, can you give me the details on how "dangerous" (or not!) my swimmer's ear drops are? And while you're at it, because now I'm curious, how does lead (probably as lead oxide) react to acetic acid and to citric acid? I'll appreciate the effort!
I hope I answered the first question above. The second question is just one about pH. What you want is a substance that is acidic enough that lead is dissolved but the other metals in the barrel are not. Acetic acid and citric acid are commonly available and probably meet that requirement (I don't know enough about concentrations and what barrels are made of to be more authoritative than that).

Lead acetate is apparently crazy toxic. Now, all lead organics are bad news, but this is apparently a strong oxidizer as well. It is a neurotoxin that is fatal if ingested (duh!), inhaled (well, it's a solid at normal temperatures, but not good) or absorbed through the skin (WTF!), and if the brain damage didn't kill, you apparently go sterile and get cancer as well. Lovely.
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
Laminar
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Jul 7, 2017, 09:48 AM
 
Originally Posted by P View Post
That is an equality reaction (not sure about the english term).
Equilibrium!
     
P
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Jul 7, 2017, 03:17 PM
 
Originally Posted by Laminar View Post
Equilibrium!
Of course! It has been too long since I studied chemistry, I forget the terms. It is all polymers if I get to do chemistry at all these days.
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
ghporter  (op)
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Jul 8, 2017, 07:41 PM
 
P, that was quite helpful. Since the "household" versions of the two items are 5% vinegar and 3% H2O2, I'd assume that the amount of peracetic acid would be pretty minimal. The de-lead application apparently takes quite a while to react completely, so that would be consistent with a dilute solution that slowly reacted with lead and/or lead oxide.

I haven't been able to find out anything about citric acid and lead. Part of the interest is now related to old "decorative" ceramics, and whether or not using a citrus-based cleaner would be a good thing when cleaning or restoring such things. I'll keep looking.

Glenn -----OTR/L, MOT, Tx
     
P
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Jul 9, 2017, 12:58 PM
 
Originally Posted by ghporter View Post
P, that was quite helpful. Since the "household" versions of the two items are 5% vinegar and 3% H2O2, I'd assume that the amount of peracetic acid would be pretty minimal.
Correct. The only caveat there is that water has the lowest boiling point of all those substances and so would boil off on a long enough time scale. In practice I suspect that the air humidity would keep things in balance, but to be safe, I would suggest clean water after the mixture has had time to work.
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
   
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