Thursday, September 9, 2010

The Physical and Chemical Properties of a Penny

istockphoto_2992953-lincoln-penny-2007-on-white-background.jpg         The penny, something we use everyday, but never take the time to examine.  A penny has many properties, both chemical and physical, that are not always apparent the the naked eye.  Based on the year the penny was made, there are a couple factors that that could cause different results.  For instance if the penny was made between 1944- 1982, then it is made of 95% copper and 5% zinc, while if made after that, the penny will be made of 2.5% copper and 97.5% zinc.  For experimental purposes, I chose to focus more on the penny made before 1982 that had a larger amount of copper in it.  The penny possibly the most simple and basic form of money has more properties than one would have ever thought.

Physical Properties

All of the properties listed below are physical because the compound itself changes, but nor the chemical composition.
  • Weight:
    • Before 1982: 3.1 g
    • After 1982: 2.5 g
  • Volume: 360 mm3
  • Color: A copper color that loses its sheen over time.
  • Circumference: 19mm
A smashed penny's weight and volume would stay the same, but it circumference would be changed.
  •  Smell: A copper/ iron smell similar to blood

Chemical Properties

All of the following properties are chemical because they involve a chemical reaction that can never be undone.

  • By putting a penny in bleach, along with cleaning the penny and removing some of the rust, dirt, ect., it produced a gritty white material on the penny.

  • By putting a penny in water it will eventually rust causing a chemical reaction.

  • By putting a penny in jewelry cleaner it removed most of the rust, dirt, and made the penny shinier.
The older penny's results were much
more noticable. The cleaner brought the penny
 back closer to its original state.

  • When i put a penny in coke there were signs that corrosion had started.  Based on my research if i had a longer period of time for the penny to sit in the coke the corrosion would be so great that the penny would dwindle down to nothing.
The older penny was the one that had shown the most progress thus far.

  • When I covered the penny with vinegar and left it over night, a green copper acetate formed much like the one on the Statue of Liberty.


  1. Katherine, I thought using a penny was a very original idea. The pictures were very good and they added a good visual component to go along with the description of your experiments. It would have been interesting to see what would have happened if you had left the penny in the coke for a longer period of time. The fact that you explained why the statue of liberty is green shows that you had a very good understanding of your experiment. But overall you did a very nice job of describing what the experiments that you conducted and the changes that occurred.

  2. Katherine, after reading your blog and then reading mine i realized there were some things we could've both including in our blogs about the chemical changes in a penny. For example we could have included wether the reaction could be classified as reverrsible or irreversible. For example, obviously if the coke diminished the penny completely it would be classified as irreverisble. Little things like that make the experiment a little bit more in depth. I also like how you used the flat penny on yours to explain how the mass and volume would stay the same but only the circumference would change. Very clever idea. Also i still think it would be could to test the flammability of a penny haha! overall great job!

  3. Katherine, you did an amazing job on your blog. The penny was a very interesting object to choose. All of your physical properties were excellent. However if you did not measure the actual volume or circumference I would have noted where you got you numbers, but only if you did not find these yourself. I liked the way you placed the pictures and comments throughout the blog. I would have made some of the pictures bigger so you can see better what happened with the penny. When putting you penny in coke what were the signs of corrosion? Why did you not keep the penny in for longer and see what would happen to it? Also I think you should have mention your reasoning for why it would have corroded. Over all you did a great job on your blog.

  4. I think that it is a very important to learn about what you put down. Thank you so much for helping me understand more of what I didn't know before.