What makes a penny look tarnished?

Question

I don't mean how you treat it . I mean what is on it that gives it that dirty look?

Answer 1

it tarnishes.  It is a chemical reaction like rust.  Some metals tarnish, some rust, etc.  silver tarnishes really bad.  There are ways to remove tarnish.  Look it up on the web.

Answer 2

oxygenisation and dirt.

Answer 3

the metal oxidizes

Answer 4

Oxidation reaction :)

Copper reacts with the oxgen in the air to produce copper oxide, which forms on the penny.

2 Cu(s ) + O2(g ) --> 2 CuO(s )

CuO(s ) + H2(g ) --> Cu(s ) + H2O(g )

Answer 5

Copper Oxide.  Presumably, you can get rid of it if you heat it up in a hydrogen atmosphere.  (The oxygen combines with hydrogen).