A silver coin with a later date may have been caused by one of two methods. First, a popular science experiment for chemistry students is to use a penny to explain how electroplating works. As part of this experiment, students dip copper pennies into zinc, which covers the copper and gives the penny a shiny silver color. Turning Copper Pennies Into Silver and Gold Pennies. When a copper penny is zinc plated it will appear to change from its copper color to silver color. And by using sufficient heat, a zinc plated copper penny can be changed to a gold color. This version of Silver and Gold Pennies utilizes zinc sulfate as less caustic than sodium hydroxide and works as well.