Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: JP on 02/08/2011 18:50:25

Title: How does salt and vinegar work to clean tarnished metal?
Post by: JP on 02/08/2011 18:50:25

This is inspired by the question on using vinegar to clean rust off metal: http://www.thenakedscientists.com/forum/index.php?topic=40446.msg363843#msg363843

The last time I had to clean some tarnished metal (I believe it was brass), I Googled around for instructions and came across a few sites saying that mixing salt and vinegar would work (with flour to make it a good scrubbing paste).  Lo and behold, it did!  I also recall that as a child, I would often drop dirty pennies into salt and vinegar in order to make them look shiny and new.

So aside from tasting great on chips (either the American or British varieties), what chemistry makes this combination so good at cleaning metal?

Title: How does salt and vinegar work to clean tarnished metal?
Post by: Bored chemist on 02/08/2011 19:37:00

CuO + 2 CH₃ COOH --> Cu(CH₃COO)2 +H₂O

You get copper acetate and water. The salt also acts as a complexing agent but the main effect is a weak abrasive.