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Question:

What happens to the silver in this reaction?

Years ago, I used to line a bread pan with aluminum foil, put in tarnished silverware or silver jewelry, along with a tablespoon of washing soda and a tablespoon of salt, pour in boiling hot water, and let it sit 5 or 10 minutesPresto, the smell of sulfur dioxide, blackened foil, and beautifully clean, shining silverIs the piece of silver losing silver in this reaction? Would you please show the formula for the reactions that are taking place? And is there any other common product that could be substituted for the washing soda, if I can't find any? Sorry for asking two questions in one.

Answer:

3Ag2S + 2Al + 3H2O - 6Ag +Al2O3 + 3H2S H2S is the sulfur you smell, not SO2The reaction works well with warm water and sodium bicarbonate (baking soda) which can replace the sodium carbonate (washing soda)I don't think the salt is contributing anything, it can be omittedThis type of redox reaction replaces the silver back onto the originally tarnished object; no silver is lostThe bicarbonate (or carbonate) serves to help remove the original oxide coating from the aluminum foil, exposing aluminum metal to the reaction solution, so the reaction may proceed.
anodizing is an electrolysis processyou cant touch it up with paintyou can get some similar paint, but an anodized part has been plated that color.

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