What Happened: Changing the chemistry of pennies and nails changed their color
Anthony (perhaps inspired by a discussion of the construction of the Statue of Liberty in history this week) wanted to see if he could make a penny turn green by soaking it in water. I suggested we also try vinegar. Nothing very dramatic happened, so I looked it up and found this great demonstration on About.com's Chemistry page:
- First we mixed 1/4 cup vinegar with 1 teaspoon salt.
- Next we dipped one dull penny in for 10 seconds, making it half shiny.
- Then we dumped about 20 dull pennies in the solution for 5 minutes.
- When the pennies were removed, some were rinsed with water, the rest left to dry as is. Within a couple of hours, the vinegary pennies had developed a nice verdigris finish.
Although it took longer than advertised, the end result was impressive. Most impressive was finding a way to do copper plating without using CuSO4 (one of the caustic copper sulfate experiments from Joy of Chemistry that I had been avoiding doing).
Update: Works on paperclips, too!
Here's a site that gives all the chemical equations involved.