How Chemical Reactions Make Old Pennies Shiny Again

SciShow Kids

In this engaging episode of SciShow Kids, host Jessi and her robot rat friend Squeaks explore the chemistry behind cleaning dirty pennies. After discovering a collection of lucky pennies that have become dull and grimy, the duo decides to conduct a scientific experiment to see which household liquids work best to restore their shine. They test five different substances—dish soap, cola, lemon juice, vinegar and salt, and ketchup—while guiding viewers through the scientific method, including setting up materials, making predictions, and observing results. The video introduces key chemistry concepts in an accessible way for young learners. It explains that pennies are made of copper and that the dull coating is copper oxide, formed when copper reacts with oxygen in the air. The core lesson focuses on how acids (found in lemons, vinegar, and cola) react with and dissolve the copper oxide, revealing the shiny metal underneath. It also explains why non-acidic solutions like soapy water fail to clean the oxidation. This video is an excellent resource for introducing the scientific method and basic chemical reactions in early elementary classrooms. It models how to set up a controlled experiment and encourages critical thinking by asking students to predict outcomes before revealing the results. The experiment uses safe, easily accessible household materials, making it perfect for a hands-on classroom activity or a home assignment that connects science to everyday life.