Name: ________________ Chamberlain Class: _______ Composition of a Penny Lab In this lab you will determine what percentage of a penny is made of copper, and what percentage of a penny is made of zinc. This lab depends upon the fact that copper is less reactive than zinc. We will use hydrochloric acid to dissolve the zinc without harming the copper. Procedure: Day #1 Get two post-1982 pennies. File 3 small grooves along the edge of each penny to expose the zinc interior. Make sure you can tell the pennies apart! Find the mass of each penny. Record the mass and the year each was minted. Place the pennies in the bottom of a specimen cup or beaker. The pennies should not touch.