On Mon, 28 Feb 2011 04:26:56 +0000 (UTC), (Don
Klipstein) wrote:

In , dilbert firestorm
wrote:

SNIP

Thanks.
there's a website that showed you how to remove zinc from a copper
plated penny.

end result, all the zinc was gone and you got a very thin piece of
copper penny left over.

don't remember which acid they used.

To the extent this is actually going to work, any strong non-oxidizing
acid should work. Hydrochloric will work, including the stuff sold as
"muriatic acid". So will sulfuric, pereferably 25-75%.

(Sulfuric acid stronger than 75% has extra dangers, and pure sulfuric
sometimes refuses to do anything until some water mixes into it.
CAUTION - add acid to water while stirring gently enough to avoid
splashing, don't add water to sulfuric acid, especially over 75% - the
water may boil, causing the acid to splash. Safety goggles or a face mask
are recommended when diluting strong or pure sulfuric acid in case
splashing occurs anyway.)

("Battery acid" is sulfuric, diluted to less than 75%.)

The point of adding salt to the vinegar is to make, one page said, a
weak solution of hydrochloric acid. NaCl + CH3COOH, which I guess
maybe gives in part HCl and NaCH2COOH.

FWIW, vinegar is only 5 to 8% acetic acid, but salt is or is near 100%
NaCL.

They spent an hour on stuff related to this both in high school and
again in college, but not exactly this and its faded anyhow. By this
I mean what reaction supercedes what other possible reaction.

My problem also probably has to do with whatever was staining the
coins in the first place, or whatever were the other substances in the
white and blue stains. If one is just making shiny coins that have
circulated and picked up fingerprint oil, that probably goes better
with vinegar and salt. Of course I have pennies like that too, and I
could try that. Since I never did it when I was 10, maybe I will now.