Shiny Penny Experiment
Have fun restoring old pennies into newer looking ones with the Shiny Penny Experiment. This experiment is great for all ages as they explore the science of chemical reactions with very quick an gratifying results.
A brand new penny is coated in shiny copper and over time it loses its luster and copper color. This happens because the copper mixes with the oxygen in the air and makes a coating called an oxide. When you put the penny in lemon juice or ketchup, the acid within each of them chemically removes the oxide, and you're left with a bright copper penny. The water, however does not have much of an effect because it does not have as much acidity as the others.
How to Do It