A new penny has a mass of 2.49 g and a volume of 0.349 cm³. Is the penny made of pure copper? Explain your answer.

Key Concepts

Density

Density is defined as mass per unit volume, typically expressed in grams per cubic centimeter (g/cm³) for solids. To determine if the penny is made of pure copper, we can calculate its density using the formula: density = mass/volume. The density of pure copper is approximately 8.96 g/cm³, so comparing the calculated density of the penny to this value will help us conclude its composition.

Material Properties

Different materials have unique physical properties, including density, which can be used to identify them. Pure copper has a specific density that can be used as a benchmark. If the calculated density of the penny significantly deviates from that of pure copper, it suggests that the penny may be made of a different material or an alloy.

Alloys

An alloy is a mixture of two or more elements, where at least one is a metal. Pennies minted after 1982 in the United States are made of zinc with a thin copper coating, which alters their density compared to pure copper. Understanding the composition of the penny is crucial for determining whether it is made of pure copper or an alloy, which can be inferred from its density.