On 9/29/14, 6:09 AM, dadiOH wrote:
>>>> I looked for a steel item that I was sure wasn't plated. I
>>>> tried a rusty screw with a penny. I got bubbles, a black,
>>>> water-soluble deposit on the penny, and copper on the screw.
>>> Right. The acid - even though weak - dissolved some copper.
>>> Those copper ions are positive. The acid also dissolved some
>>> iron; those ions are also positive leaving the screw negative.
>>> The copper ions are >
>>> strongly attracted to the screw than are the iron ions. The
>>> bubbles were hydrogen gas. The black would be an iron salt.
>> I wonder why the bath wasn't blue. Maybe there was very little
>> copper in it at any time, or maybe it was in some form besides CU++
> Perhaps it would be if there were more? If a copper compound it
> could be blue or green, Copper when burned can produce a flame that
> is green (usual), blue, red or colorless depending upon temperature
> and whether the flame is anoxidizing or reducing one.
I've read that you can put pennies in a vinegar-salt bath, remove them,
put in an iron item, and pull it out plated. I'll believe that when I
I wonder if my copper-plated screw is now rustproof.