Order early for pre-holiday delivery. Flinn will be closed December 24th, 2025,
through January 4th, 2026, reopening Monday, January 5th, 2026.
Orders received after 10:30 AM Central Time on Tuesday, December 23rd, 2025,
will ship after we return.

Publication 10517
Price: FREE
Pennies minted before 1982 were made entirely of copper. Pennies minted after 1982 have a core of zinc that is plated with a very thin layer of copper. This experiment demonstrates the different reactivities of zinc and copper with an acid.