Chemistry For Pennies
Three dirty old
pennies | Measuring spoons
Vinegar | Lemon juice
| Ketchup | Salt
Clean, new steel nails
Three small non-metal
cups (small, recycled plastic containers are great)
Craft sticks for
stirring | Paper towel | Pencil
a tablespoon of vinegar into a small plastic cup. Add one-fourth teaspoon of
salt. Stir until the salt dissolves. Put the first penny into this solution.
What do you see? Leave the penny in there for five minutes. Then take it out
and let it dry on the paper towel. Write "vinegar" underneath it.
reason pennies get dull is that the copper in them gradually reacts with the
air to form "copper oxide." Pure copper is bright and shiny, but the oxide that
comes from contact between copper and oxygen is a dull, brown color.
NOT throw out the vinegar-salt solution. Instead, lean a steel nail against the
side of the plastic container so that the metal is half in, and half out of the
vinegar-salt solution. Leave the nail there for 10 minutes. You may see some
bubbles! That means a chemical reaction is taking place. Is the nail in two
tones now? That's because the copper that the vinegar removed from the penny
has now shifted to the surface of the nail.
try the penny-shining test in another container with a tablespoon of lemon
juice and a quarter-teaspoon of salt, and a third container with the same
quantities of ketchup and salt. There's a lot of acid in lemon juice as well as
in the tomatoes that are the main ingredient of ketchup. Rinse the craft stick
you use for stirring with water in between stirring tasks.
the two other pennies in the lemon juice and ketchup solutions for five
minutes. Remove. Place them on the paper towel, labeling them underneath as
"Lemon Juice" and "Ketchup," so you can remember which is which.
type of acid worked best? Why do you think?
you have an old toothbrush around, polish your pennies even more with a little
more vinegar, lemon juice or ketchup, and some salt. The friction (FRIC-shun)
from rubbing the toothbrush bristles should make the pennies even shinier.