1 corroded penny (one with powdery green corrosion is best)
1 cup of water
½ cup of baking soda
1 piece of aluminum foil, about 4 x 4 inches.
A glass bowl
What to do:
1.
In the glass bowl, mix the water and the baking soda; this is your electrolyte. (It’s OK if not all the baking soda gets dissolved.)
2.
Loosely wrap the penny in the aluminum foil (it has to be loose so the electrolyte can get in but make sure the penny and the foil are touching).
3.
Place the wrapped penny in the bowl.
4.
After one hour, take out the penny and unwrap it.
5.
Examine the penny. Does it look different? If not, rewrap the penny in the foil and put it back in the electrolyte for more time.
Why it works:
In the galvanic cell you made, the aluminum is the active metal and the copper is the more noble metal. The aluminum undergoes corrosion and the copper undergoes reduction (the opposite of corrosion). So the green, powdery stuff that was on your penny has been reduced back to metal.
Things to think about:
Seawater is an excellent electrolyte. If the Monitor was found in fresh water instead of the salty Atlantic Ocean, do you think the metals would be as corroded?
How could an active metal (like the aluminum you used in the experiment) be used to protect the Monitor from further corrosion on the ocean bottom?
Galvanic cleaning is not used for artifact conservation because it is hard to control the reactions. It also does not remove salts very well. Why is it important to remove salts from metal artifacts?
