From 1793–1857 pennies were made of 100% copper. Since 1857, the composition of the penny has changed several times. In 1982, there was a drastic change amount of copper a penny contained.

In this lab, you will use the physical property of density to determine the composition of pennies minted before and after 1982.

Copy the following data table onto your own paper.

1. Place all seven of the pennies minted prior to 1982 on the balance and determine the mass of the pennies. Record in the data table.
2. Measure 5mL of water in the graduated cylinder.
3. Place all your pennies dated prior to 1982 into the water. Determine the amount of water displaced by the pennies. (Final volume: 10mL) This will be the volume of the pennies. Record in the data table.
4. Calculate the density of the pennies. Use the formula Density = m over v m v .
5. Repeat the procedure for the pennies minted after 1982.

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Hint

	Mass (g)	Volume			Density (g/mL)
		Initial Volume	Find Volume	Volume of Pennies (final-initial)
Pennies minted prior to 1982	22.1	5	7.5	2.5	8.84
Pennies minted after 1982	21.6	5	8.0	3.0	7.2

Based on the average density and the chart below, what were the pennies minted prior to and after 1982 made of?

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Check Your Answer

Pennies minted prior to 1982 are made up of mostly cooper.

Pennies minted after 1982 are made up of mostly zinc.

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