Chemistry Reference
In-Depth Information
mass
volume
Density =
As your volume increases, the denominator in the formula increases and your
density decreases, helping you to float.
Figure 2-6a
Have you ever tried to sink and lie down on the bottom of a pool?
How did you do it? Did you try to expel as much air from your lungs as you
could? If you did, your chest contracted, decreasing your volume and in-
creasing your density.
mass
volume
Density =
As your volume decreases, the denominator in the formula decreases and
your density increases, allowing you to sink.
Figure 2-6b
In order to calculate the density of a material, you need to know its
mass and volume. Both of these properties can be easily measured in the
laboratory, using the methods described in Lesson 2-2. Let's imagine that
you place a rock on a balance to measure its mass and find it to have a mass
of 22.516 g. You then use the water displacement method to determine the
volume of the rock, which you find to be 7.84 cm
3
. You would then use the
density formula to find the density of the rock, as shown here:
Example 1
Find the density of a rock with a mass of 22.516 g and a volume of
7.84 cm
3
.
Given: mass = 22.516 g
volume = 7.84 cm
3
Find:
density
mass
volume
22.516 g
7.85 cm
3
= 2.87 g/cm
3
Density =
=
