Any chemists out there?

[TillEulenspiegel]

A silly question.

I live in Florida (US) and it's extremely humid.
I have a salt shaker that is glass with a metal top. If left long enough that top 1/3 of the salt will turn green, like the oxide patina on brass or copper statues. Obviously there is an electrolytic process going on...but what is the green compound ( salt)?

 

[baggie]

you dont say what the metal is - stainless steel, brass ? The green colour suggests copper, so it is probably a cupric salt, depending on the conditions probably a mixed cupric chloride/oxide

 

[TillEulenspiegel]

Hmm don't really know the composition of the cap ( plastic coated w/ a "chrome " finish) but thats what it looks like....so the electrolitic process is actually leaching copper into the salt?

 

[Iamme]

Till---You didn't tell us if you had kids. I would first ask each and every one of them if they have been popping lugies into the salt!

 

[baggie]

If it was stainless steel then the salt colour could be chromium based. It is impossible to give a simple formula for the salt, but it will contain sodium, chloride, chromium and oxide/hydroxide ions. The green colour is probably Cr3+

 

[patnray]

Chrome is always plated on top of copper. Plastic parts are chemically plated with copper and the chrome is electroplated onto the copper. Copper salts, as mentioned above, are usually greenish blue. Perhaps the humid salt is detaching the copper undercoat from the plastic?