Date Uploaded: September 6, 2009, 10:02 pm
Last Edited: August 7, 2012, 5:52 pm
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Easy Kitchen Silver Polishing
Article © MAIL User: Tesserex
I have done more research and learned how exactly these reactions work. I also notice that many people discussing this topic reference the same rip-off commercial that I saw.
Remember that this cleans silver sulfide (Ag2S) tarnish that is caused by exposure to the hydrogen sulfide of the atmosphere. It its brassy looking, so if your silver looks like dull brass, clean it this way.
The best part? I guarantee every one of you has the materials to do this right now in your kitchen. You will need:
1. A vessel large enough to hold the piece. For jewelry, a bowl will do.
3. Baking Soda - (NaHCO3)
4. Aluminum Foil
5. Heat (A microwave will do)
First, if you plan to use the microwave for heat, you must heat the water in an alternate vessel. This is because you want to put the aluminum foil in the bottom, and
1. you don't want to push the foil down to the bottom of a vessel of scalding hot water, and
2. You don't want to put the foil in first and then in the microwave...
So, heat enough water to fill the vessel to cover the piece. Dissolve in a little bit of salt and a very liberal amount of baking soda.
Now place the foil on the bottom of the vessel and pour the water into it. Now just place the piece in the vessel, IN DIRECT CONTACT WITH THE FOIL! This reaction is electrolytic, hence the salt.
You should see bubbles forming, these are hydrogen and hydrogen sulfide. Not enough to worry about. If you don't see enough of an effect after about 20 seconds, sprinkle more baking soda into the water directly onto the piece or aluminum.
How this works:
1. Aluminum has a lower ionization energy than silver. This means that in a fight for sulfur ions, aluminum wins.
2. 3 Ag2S + 2 Al = 6 Ag + Al2S3
The aluminum steals sulfur atoms from silver sulfide, forming aluminum sulfide. Easy, right?
3. Al2S3 + 3 H2O = Al2O3 + 3 H2S
Aluminum sulfide is sensitive to water and immediately hydrolyzes to form aluminum oxide and hydrogen sulfide, which smells bad when it bubbles up.
However, we have a problem. Aluminum is very reactive with air, so all aluminum you use has an oxide layer already present on it. This prevents the sulfur from getting through to aluminum metal. This is where baking soda comes in.
4. NaHCO3 + H2O = Na+ + H2CO3 + OH-
These OH- ions make the solution basic, which then somehow corrodes the aluminum oxide layer, exposing fresh aluminum for the reaction.
Finally, baking soda serves one other purpose. It reacts with the produced H2S to produce CO2 and something else, either sodium sulfate or sodium thiosulfate, something like that. The bubbles won't smell so bad because of that.
Original URL: http://www.mailleartisans.org/articles/articledisplay.php?key=399