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%.)
--
- Don Klipstein )