Eighth-grade chemists delved into the ancient art of alchemy, or the supposed transformation of matter. Medieval people thought it possible to turn inexpensive metals into precious resources like gold. Our students learned that looks can be deceiving and had fun with chemistry in the process.
Eighth-Grade Science Teacher William Bander explained that the students had already completed a summer work assignment that dealt with the field of chemistry evolving out of the now-defunct field of alchemy. They came into the lab with the intent to make silver and gold pennies.
Using simple ingredients, the student scientists set about transforming pennies. First, they cleaned pennies in water with vinegar and salt. This process removes oxides from the pennies. The cleaned pennies were then submerged in new mixture of water and dissolved sodium hydroxide, commonly used as drain cleaner, and zinc metal. When heat is added, the pennies slowly become coated in zinc. They end up looking silver. After drying the now-silver pennies completely, students placed them on hot plates. They watched as the pennies slowly changed color, turning from silver into gold.
«I really enjoyed the experience of the lab,» said Cate Wagner ’29. «I was able to learn a lot about how mixing metals worked and a little bit of the periodic table. I also learned how different metals can mix together and create completely new metals. My favorite part was being able to see the process of the pennies turning silver and gold.»
«Sadly, no silver or gold was used as the starting materials,» said Bander. «So, despite how the pennies looked, they were not actually silver or gold.» After the transformation, they learned what their pennies became based on the ingredients they had used. «They were able to deduce that the silver coating was actually zinc and, with some engagement from our band students, they deduced that the gold color came from zinc and copper melting together to form brass—the same alloy in trumpets and tubas.»
Simone Glasser ’29 said, «My favorite part of the penny lab was when we placed our ‘silver’ pennies directly onto the hotplate. It was incredible to watch the pennies turn ‘gold’ in just a couple of seconds. A day later we learned that the ‘gold’ pennies we made were actually brass! Brass is the combination of copper and zinc, the same thing trumpets are made of.»
«This served as a great introductory lab into chemistry as it allowed students to contrast this modern scientific field with the archaic field of alchemy,» said Bander. «It also demonstrated the conservation of matter and how you can’t magically produce something like gold if your starting metals do not contain any gold.»
Alexa Sikorski ’29 enjoyed the lab. «The penny lab was really fun to learn about,» she said. «The heat from the hot plate changing the silver penny gold was very interesting. When we went over the lab and figured out that we created brass, it was very engaging and cool. I really enjoyed the lab, and I hope that next year’s eighth graders get to participate!»
Students were allowed to keep their transformed pennies as a «back-to-school present» from their science teacher.
Well done, student alchemists! May your «gold» pennies be sweet souvenirs of your learning experience.