Six Ways to Clean a Penny: A Simple Science Experiment

Most of us probably remember the classic science experiment of cleaning a penny with a mixture of vinegar and salt. There is always something so magical and exciting about tossing in a dirty penny and seeing a beautiful clean and shiny penny come out. Well, my seven year old and I decided to take the experiment one step further. What else could we use to clean a penny?

We assembled various solutions from what we had around the house. Lemon juice, cola, ketchup, tabasco sauce and just plain old water. I had read about trying tabasco sauce and ketchup somewhere once so we were anxious to see what it would do to the pennies, if anything.

We tossed in our six tarnished pennies and waited for about ten minutes before we allowed ourselves to check on them. While we waited, we hypothesized. Which solutions might work? Which ones might not work? Which solution did we think would work the best?

After ten minutes we dried our pennies with a paper towel and examined the results. We asked questions like…Which solution produced the shiniest penny? Were you surprised any of the solutions worked? After a little studying we decide to see what would happen if we let the pennies soak a little longer. We popped them back in to their corresponding bowls and left them to soak for another twenty minutes.

In total after an half an hour we had a fair share of shiny pennies. Some solutions worked better than others. The water didn’t really work at all, and we pretty much knew that it wouldn’t going in, but we wanted a baseline to compare our results to. We cleaned off our pennies one last time and studied them again making observations and asking questions as we went along. Some of our observations were very interesting. For example, the penny that was cleaned in tabasco sauce had gotten cleaner but it had a slight tinge of color to it. The ketchup penny was fairly shiny and that surprised us. The penny in the lemon juice seemed to be the shiniest. I think you get the idea Try it! Have some fun cleaning pennies. Try different solutions, hypothesize, and then talk about your results as you observe them. It was certainly lots of fun for us. Ask your child some of the questions we used or just ask them to tell you about their observations and see what they come up with on their own. You may be surprised.

Another fun piece of this project was to line the pennies up after the fact and see if we could guess which penny was cleaned in which solution by remembering what we observed. Can you tell which penny was cleaned with just water? Can you tell which one was cleaned in the tabasco sauce? Hint: use all your senses…we could tell which penny was cleaned in the ketchup from the smell. What other solutions can you think of to use to try and clean pennies?