# Pennies Lab Essay

393 Words2 Pages
Density of Pennies Lab Introduction “The one cent coin, commonly known as the penny, was the first currency of any type authorized by the United States.” (www.pennies.org, pg.1)The first penny was made in 1787, composed of pure copper. They continued to produce pure copper pennies until 1837 when they switched to bronze. In 1857 they began using copper and nickel. The composition of a penny changed twice more before 1982. The pre-1983 penny was made of an alloy of copper and zinc. An alloy is “a substance that has metal characteristics and consists of two or more different elements”. (Coordinated Science, pg.1005) Our objective is to find the metal used inside a post-1983 penny. The accepted value of the density of a post-1983 penny is 7.05g/cm3. “Density is the mass per unit volume of a material”. (Coordinated Science, pg. 354) By calculating the density of post 1983 pennies, we can compare it to the given density values of other metals to find the metal used in the core of a penny. Conclusion The metal used inside post 1983 pennies is zinc. We came to this conclusion by calculating the density of post 1983 pennies using the equation; massvolume=density. WE conducted three trials of this experiment and found the average density of a penny to be 6.92 g/cm3. The accepted value of a post 1983 penny is 7.05g/cm3. Our percent error was 1.8%. In order to have valid results, your percent error must be equal to or below 3% and ours was below. Once we found our results to be valid, we compared our average density to the density of the given metals. The density of zinc, 7.00 g/cm3, was the closest density in range of our calculated density. Our procedure had to be adjusted three times in order to find accurate data. Our original procedure didn’t measure mass or volume correctly. After adding in the correct steps, we conducted the experiment successfully. Once our