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topic 2867

Penny Science Project


1999

I am doing a project on removing tarnish from pennies using coca cola, sprite and water. I can't find out what the chemical reaction is, or why it should work. Can you suggest help?

Eric N.
- Duncan B.C. Canada


The chemical reaction is acid dissolving tarnish, Eric..

There may be several different acids in soda, and the tarnish may consist of various oxides, sulfides, and carbonates, so there is not a single simple equation. But here is one balanced equation that is probably one of the reactions --

2H3(PO4) + 3CuO => Cu3(PO4)2 + 3 H20

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey


(2002)

I think that lemon juice cleans pennies the best.

Lundon G.
- California


2003

Well Eric, I did a project on that but instead of water, I put Dr. Pepper. It was Coke that cleaned it the most and I found this out on this website: www.finishing.com/134/43.shtml It said: "Acids have power to remove copper tarnish because copper oxide dissolves in acid; the stronger the acid, the more dissolution power." Hope it helps. See ya.

Stephen M.
- El Paso, Texas, U.S.A.


Ed. note: Please see our F.A.Q. on this subject smiley



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