Pass the bag around the room. Disposal Pour the water down the drain. Wrap the penny skins and zinc core in paper before discarding them in the trash. Before 1982 copper was the primary component of a penny. Late in 1982 the composition of a penny was changed.
Copper has a much higher melting point than zinc does.
As you saw in the demo, the heat of the burner flame was hot enough to melt the zinc, but not the copper. If you watched the flame closely, you saw the characteristic blue-green color that copper emits during a flame test. Put each penny in a separate labeled bag, and pass them around for your students to see. In this 5-lesson unit, students explore the physical, chemical, and magnetic properties of US currency and coinage. After measuring the dimensions of a bill, calculating its surface area, and measuring its volume, students design a procedure to determine the thickness of the bill by incorporating lab techniques they have just learned.