May 13 2009
Clean Them Pennies
Do you have some old pennies that need a cleaning? Today, we will explore dirty pennies and how to get them all shined up again so they look like they just rolled off the mint. Pennies are manufactured with a coating of copper, they used to be all copper at one point, and then various metals were used, with zinc being the primary metal in today’s penny.
The copper outer layer of the penny; will over time, oxidize as a result of being exposed to the air, thus copper oxide is formed (the dull and greenish look). We will create a little solution whereby you can bathe the pennies and return them to their shiny appearance.
You will need ¼ cup of white vinegar, 1 teaspoon of salt, a clear glass or plastic bowl (not metal), and some water to wash the pennies after you pull them out of the bath. Mix the vinegar and salt in the bowl (until the salt dissolves) and then dump in the pennies you wish to clean. The cleaning action will be visible for a few minutes – leave the pennies in the solution for about five minutes. The acid of the vinegar will dissolve the copper oxide.
After about five minutes, the pennies will be nice and shiny – remove them from the solution and then wash them down in water to stop the solution from working – then dry them on some paper towels. Before you toss out your penny cleaning solution, you may wish to have a little bit of fun and make some copper coated nails – visit http://chemistry.about.com/cs/demonstrations/a/aa022204a.htm for a fun experiment using the solution you used to clean your pennies. You will also learn more about the oxidization and why it takes place. Enjoy and have fun!
