|MadSci Network: Chemistry|
Pure (?) vinegar should be a solution (~5%) of acetic acid in water. Silver does not react with water. Because of silver's low reactivity and the weak nature of acetic acid, I would not expect any reaction here either. It is well known that silver (plate or otherwise) reacts with sulfur compounds, those found in the air (hydrogen sulfide, sulfur dioxide, etc.), to form the dark color of the tarnish. It is also known that the sulfur in proteins can cause similar tarnish on silver. Eggs are a particularly good source of this type of tarnish. I would wonder about what minor (sulfur containing?)contaminants might be in the vinegar used in this case. The food that may have been in the container used for the vinegar may be a source. These are my best guesses. Yes, there is an electrochemical angle to all of this since the silver is losing electrons to become the silver ion in the tarnish compounds. Sorry that it took me a while to get you this answer. Jerry Franzen Chemistry Department Thomas More College 333 Thomas More Pkwy. Crestview Hills, KY 41017 606-344-3377
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