Density Chemistry Example 2

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Example 2

medium

A piece of metal has a mass of

78.0

g. When placed in a graduated cylinder containing

25.0\,\text{mL}

of water, the water level rises to

35.0\,\text{mL}

. Calculate the density and identify the metal if possible. (Iron =

7.87\,\text{g/cm}^3

, Copper =

8.96\,\text{g/cm}^3

, Zinc =

7.13\,\text{g/cm}^3

)

Solution

1
Volume of metal $= 35.0 - 25.0 = 10.0\,\text{mL} = 10.0\,\text{cm}^3$ .
2
$\rho = \frac{78.0}{10.0} = 7.80\,\text{g/cm}^3$ .
3
Comparing to known densities, $7.80\,\text{g/cm}^3$ is closest to iron ( $7.87\,\text{g/cm}^3$ ).

Answer

\rho = 7.80\,\text{g/cm}^3 \approx \text{Iron}

Water displacement is a classic method for measuring the volume of irregular solids. Density can then be used as a fingerprint to identify unknown materials.

About Density

The mass of a substance per unit volume, measuring how tightly packed the particles are within a material.

Learn more about Density →

More Density Examples

Example 1 easy

A block of aluminum has a mass of [formula] g and a volume of [formula]. Calculate its density.

Example 3 easy

Will an object with density [formula] float or sink in water ([formula])?

Example 4 hard

A solid cube has a side length of [formula] and a mass of [formula]. Calculate its density. If the c

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Related Concepts

Physical Property Mixture Separation