![]() Hmmmm….can you explain the differences observed in the two pennies above? Why is one penny melted and the other is not? Why does the melted penny have a slight grey color? Why did the un-melted pennies have red, orange, and brown hues? Why were some of the un-melted pennies black in color (Figure 2)? I’ll leave the reader to answer these questions. Upon doing so, I found the following (Figure 1).įigure 2: Another penny retrieved from the campfire ash I would often retrieve the pennies from the campfire ash the day after doing penny experiments. I’d certainly be interested if anyone discovers that green flames can be produced from patinas generated with something other than the ammonia-salt mixture.įigure 1: Comparison of two pennies placed in a campfire and retrieved from the ash the following day. Maybe you’ll invite your students to investigate the same questions. Could it be that the patinas formed via treatment with ammonia form more basic copper salts on the penny due to the greater basicity of ammonia as compared to baking soda? If so, might more basic copper salts allow for more facile generation of Cu(OH) (g) as the campfire flame interacts with the penny patinas? I will definitely be posing these questions to my students as potential questions for exploratory projects. I was able to track down several papers 2 which demonstrate that emission from transient Cu(OH) (g) is responsible for the green color associated with flame emission from copper salts. I’m not sure why this is, but I have some guesses. Interestingly, it was only the pennies treated with the ammonia-salt mixture that displayed the green flame when placed in the fire. I used two different paper towel-soaking "recipes" to form patinas for the campfire experiments: a) a 6% solution of baking soda or b) a 6% solution of table salt dissolved in household ammonia. Isn’t that cool? You can create green flames in your campfire with copper salts that are formed using only pennies, household ammonia, salt, aluminum foil, paper towel, and a 9V battery. Video 2: How to make a green flame in a campfire, Tommy Technetium YouTube Channel, accessed (7/28/20) ![]() Watch Video 2 below to see what I learned: Because many copper salts generate a green color when placed in a flame, I thought it might be fun to place some coated pennies in my campfire. ![]() Video 1:The Chemistry Behind Why the Statue of Liberty is Green, Tommy Technetium YouTube Channel, accessed (7/28/20)Īs you can see in the video, copper patinas are comprised of copper salts. You can learn a little more about these experiments in Video 1 below: This experiment provides students with hands-on access to experiments that illustrate how the green color forms on the Statue of Liberty. Deanna Cullen, Scott Milam, Doug Ragan, and I recently published an article, Rapid Formation of Copper Patinas: A Simple Chemical Demonstration of Why the Statue of Liberty Is Green, in the Journal of Chemical Education 1 that describes how to create a blue-green patina on the surface of copper coins. ![]()
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