You find a penny with a mass of 2.50 g and a volume of 0.339 cm3. is this penny pure copper? (the density of copper is 8.96 g/cm3)

Given:

Mass = 2.50 g

Volume = 0.339 cm3

Find:

Density = ?

Solution:

In order to check if the penny is pure copper, we need to find the density of the penny and compare it with the density of copper which is 8.96 g/cm^3.

Density = mass / volume

2.50 g / 0.339 cm^3 = 7.37 g/cm^3 

So, from what we got, the penny is definitely not copper. It is mostly Manganese which has a density 7.43 g/cm3.

The properties of the copper/nickel alloy used in the previous Susan B. Anthony dollar was intended to be duplicated by the manganese alloy, in the case of the later U.S. dollar coins.