well how do pennies change color this for my science report and i have been to so many sights i can not find a answer so if you do have a site i can use please give it to me please well i have to go w/b soon someone
2007-01-18 04:21:30 · 4 answers · asked by dog_see_bye 1 in Education & Reference ➔ Homework Help
Pennies discolor due to oxidation... the same process responsible for causing iron to rust. Oxygen combines with molecules on the surface of the metal to form oxides of the metal. With iron, the result is Iron Oxide - or rust. With pennies, the oxidation products differ, depending on the mint date of the coin.
Prior to 1982, pennies were comprised of close to 95% copper. When the surface of these pennies oxidize, the primary product is copper oxide... which gives the coins a striking green appearance. Since 1982, pennies have been composed primarily of zinc, with only about a 2% copper content. While zinc is less reactive than copper, when it does oxidize, it produces more of a dull, darker brown appearance.
Hope this helps.
2007-01-18 04:35:46 · answer #1 · answered by Just Some Guy 3 · 0⤊ 0⤋
Its a natural process known as oxidation
2007-01-18 04:26:14 · answer #2 · answered by papamillion2002 1 · 1⤊ 0⤋
oxidation causes copper to change their color
2007-01-18 04:29:45 · answer #3 · answered by paco 1 · 0⤊ 0⤋
they turn a funky green color with age
http://www.coins.com
2007-01-18 04:25:44 · answer #4 · answered by sunflare63 7 · 0⤊ 0⤋