[MrOHBrown]

Hey guys,

I am a chemistry teacher but haven't had my own lab until this year, therefore a lot of years went by without me tinkering, but on the up-side I have been doing a lot of my own experiments on the side now that I can. The kids really enjoy it, not the least of which was the shiny silvery substance I produced by adding a Cu electrode to 0.1 M AgNO₃ solution.

I want to be able to refine this further. Greyish-black by-products have formed which I put down to unavoidable oxides and other inpurities caused by a not-quite 100% clean Cu electrode. I placed the silver/solids in a test tube under vacuum and heated it hoping to decompose the compunds but with no luck.

Does anyone know what these substances are and how I may seperate them from silver? Decanting? Flotation? I'd try myself but I have already used enough silver solution that I wanna avoid trial and error at this time.

Also, the silver is in tiny little spikes, which should be easy to melt. I tried to heat it under vacuum (to avoiding burning) so that it would melt into a solid, but this caused the TT to warp so I had to abort.

Can anyone suggest how I may, once impurities are removed, turn the silver flecks into one solid mass?

My students ask "Can you make money that way" - Yes, but I'd lose more in the process! Ha ha

[Arkcon]

Greyish-black by-products have formed which I put down to unavoidable oxides and other inpurities caused by a not-quite 100% clean Cu electrode. I placed the silver/solids in a test tube under vacuum and heated it hoping to decompose the compunds but with no luck.

It is also possible that they are silver as well.  Finely divided metals often look like black or grey powders, c.f. platinum black.

Also, the silver is in tiny little spikes, which should be easy to melt. I tried to heat it under vacuum (to avoiding burning) so that it would melt into a solid, but this caused the TT to warp so I had to abort.

When trying to smelt metals, you'll want a very hot flame, and some sort of refractory vessel.  There are porcelain crucibles for this purpose, shaped as a truncated cone to force liquid metal to collect.  To prevent oxidation, you may want to add carbon, and a flux -- boric acid is a nice one for hobbyists, it melts to a nice glassy crust.  You may also want to look up cupellation, it is an important topic in precious metal assaying.

We're kicking around a very similar topic in this thread here:
http://www.chemicalforums.com/index.php?topic=22017.msg84191#msg84191

*[EDIT]* one misspell

[MrOHBrown]

Thanks