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The Earth’s Density
Name: _____________
Blk: ______
Purpose: To examine earth composition by calculating and comparing the densities of different
earth materials.
Background Information: The Earth is made up of many layers. This is the result of it
undergoing planetary differentiation, where denser materials sink to the center to form the core
while lighter materials form around the outside. Whereas the core is composed primarily of iron
and nickel, Earth’s upper layer are composed of silicate rock (Basalt & Limestone) and minerals.
Basalt, an igneous rock type, underlies more of Earth's surface than any other rock type.
Limestone is also found in the earth crust, but is a sedimentary rock type.
Density is a measure of the amount of material (mass) in a given space (volume), and can be
calculated using the following equation:
Density = __Mass__ or D = M__
Volume
V
e.g., A small block of lead has a mass of 90.4 g and a volume of 8 mL.
Density of lead = __Mass__ =
Volume
90.4 g
8 mL
= 11.3 g/mL
Equipment:
Graduated cylinders, Water, Scale, Samples of limestone, basalt, pumice, iron and nickel
Procedure:
1. Use the scale to determine the mass of your sample (in grams).
Record your result in Column 1 (Mass of Sample) in table 1.
2. Fill your graduated cylinder enough to fully cover your sample and record the volume in
column 3 in table 1.
3. Place the sample in the graduated cylinder, making sure it is fully submerged. You may need
to hold the sample down with the tip of a pencil if it floats. Record the volume of the water and
sample together in Column 2 of table 1.
4. Subtract the values in Column 3 from Column 2 – this gives you the volume of your sample.
Place the result in Column 4 (Volume of Sample)
5. Calculate the density of your sample by dividing the mass of your sample by its volume.
Record the density in Column 5.
Table 1:
Sample
Column 1
Column 2
Column 3
Column 4
Column 5
Mass of
Volume of
Volume of
Volume of
Density
sample (M)
Water +
water (V)
sample (V)
(M/V)
(g)
Sample
(mL)
(mL)
( g/mL)
Limestone
Basalt
Pumice
Nickel
Iron
Questions:
1. a) Which sample was the least dense? ________________
b) Which sample was the densest? _________________
2. The density of water is 1 g/mL. Explain why the least dense sample floated on water.
3. How do the densities of nickel and iron as compared to those of crustal rocks (Limestone &
Basalt) help explain the structure of the Earth?
4. The overall density of the Earth is 5.5 g/mL, while the average density of the Earth’s rocks is
only 2.8 g/mL. How can this be?
Conclusion: (Discuss the results of the lab, in relation to the purpose listed on the top of the lab sheet).