Lucky Pennies

We started off March, the month of St. Patty's Day, leprechauns, green, pots o'gold, rainbows, shamrocks and the like, with an experiment to make some lucky pennies.

A friend of mine had done this experiment with her own child, and had referenced me to the book from which she found the activity. It is called, Everything Kids' Science Experiments Book, and you can check out a few of the pages if you click on the link. Anyway, it was one of the more successful science experiments that we've attempted so it gets a good rating from me.

It's called, "Cleaning Pennies," and it's very simple. All you do is dump dirty pennies into a mixture of vinegar and salt. After a few minutes the dirty pennies will be much cleaner and shinier.

If you rinse the pennies under the tap they will remain bright and shiny. If you pull the pennies out of the solution and leave them to dry without rinsing them, they will turn greenish, bluish, grayish. The only hard part about the experiment is that you have to wait quite a while for the greenish color to develop. For our pennies to really get a good coating of green/blue/gray it took a few hours. On the other hand, the cleaning process is really very quick and will yield excellent results in a matter of minutes.


Before performing the experiment, I remembered I had seen something similar in one of my favorite blogs, Mom to 2 Posh Lil' Divas , so I checked it out really quick just to make sure the two sources agreed. I'm glad I did because I thought the Posh Diva site added a couple of great extension activities to the experiment that really made a difference for us. For example, the author added two additional solutions to test: pure water and a soap/water mix. Then her girls put pennies in all 3 cups and compared the results. So when we did our experiment, we did the same thing:

(L to R: water, soapy water, vinegar/salt)

It was interesting to get the boys' predictions and test them against the results. Of course, the vinegar solution wins the contest, but having the other two solutions gave me a chance to talk to the boys about various cleaning agents and how they work.

Now all we have to do is decide which is more lucky: a shiny penny, or a green penny?