Chemical dopers, question on silver tarnish chemistry

Factual Questions
1

Hi all,

So as the title says I’ve got a question that kind of came out of this thread. http://boards.straightdope.com/sdmb/showthread.php?t=573575

So basically I know how I can use electro-chemistry to convert silver sulfide back to silver with aluminum and an electrolyte solution. Suppose I had 2 silver coins or spoons. One had been kept in an inert atmosphere so had never tarnished. The other had tarnished but had been restored like this video demonstrates http://www.youtube.com/watch?v=vGCx9HZwYBo

Would you be able to see through say a microscope that the second coin had been restored but was an original surface? (Obviously there won’t be any scratches which would be the case for polish but would anything be obvious on the treated coin under a microscope or anything?)

2

the reformed metal atoms would not be in the same position as the original metal atoms and this would be visible.

3

While I haven’t seen such a coin, I’m also confident that the atoms that were redeposited wouldn’t have the same “mint lustre” that an uncleaned coin would. It would be obvious to the naked eye, at least to a coin dealer or good collector.

4

It depends on what you mean by looking down a microscope. If you’re talking about literally looking down a light microscope then I would say no, there would be no discernible difference between the restored coin and the original that had been kept under dry argon (say) for 100 years. The macroscopic properties of the metal surface would not manifest any visual effects of the redox cycle.

If you’re talking about a microscope in the wider context, say a more powerful scanning electron microscope, or an atomic force microscope (that one doesn’t look down, strictly speaking), then maybe you could see the difference - I don’t know enough about surface science to say for sure. It’s likely that the thought experiment breaks down here anyway, as the difference in surface chemistry / structure between a coin held in laboratory conditions and the wild type would be enormous anyway even without the redox chemistry.