I remember from chemistry class it has to do with oxidation, but I'd like a little more explanation. More importantly, I'm wondering the chemical processes behind how "Barkeeper's Friend" powder scrubs it back to shiny new in an instant and what causes the formation of that horrible stench?Chemists, can you explain the chemical process for why my copper- bottomed pans turn black...?
remove the oxygen again.Chemists, can you explain the chemical process for why my copper- bottomed pans turn black...?
copper has 2 oxidation states, cuprous (copper (I)) and cupric (copper (II)).
as the pan begins to oxidize, it turns a dull red. you might not even notice this step. this is the oxidation to a cuprous oxide layer forming from heating the pan in the presence of air.
as the oxidation progresses, the layer will form cupric oxide, and the pan will get closer to black in color as the oxide layer continues to develop.
Barkeeper's Friend is Oxalic acid. it is an organic acid produced by the oxidation of Methyl Alcohol.
this acid dissolves the oxide layer forming copper oxylate. the smell is probably formaldehyde which is formed by the reduction of the acid by the fresh copper acting as a catalyst.
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