Determining the Density of Unknown Objects
Name:
Introduction:
Why don’t objects that have the same dimensions always have the same weight? Density!
Density is the way we measure the amount of matter in a certain space or volume. This can be expressed in the
following mathematical equation:
Millimeters (mL) is a useful unit for liquids since it is very difficult to measure the dimensions of a liquid with a
ruler. But the solids, which don’t fill the container they’re in, cubic centimeters (cm3) is a much more useful unit.
In part A, you will calculate the volume of a cube using a ruler and then determine the density of the cube to
determine the type of metal found in the unknown cube. In part B, you will use water displacement to
determine the density and identity of the unknown cylinder.
Problem:
Determine the identity of the unknown metal cubes and cylinders using density.
Materials:
Part A
 unknown metal cubes
 ruler
 digital scale
Part B
 unknown cylindrical objects
 50 mL graduated cylinder
 digital scale
Procedure:
Part A – Determining Density by Measuring the Volume of Metal Cubes
1. Obtain a metal cube from your teacher. Write down the number found on the cube.
2. Use a ruler to measure the length, width and height of the cube in cm. Write this value in the observation
chart.
3. Use a digital scale to measure the mass of the cube. (Do not forget to re-zero/tare the scale before
determining the mass.) Write this value in the observation chart.
4. Repeat steps 1-3 with another cube.
Part B – Determining Density by Water Displacement
5. Obtain a cylindrical object from your teacher. Write down the number found on the cylinder.
6. Use a digital scale to measure the mass of the cylindrical object. (Do not forget to re-zero/tare the scale
before determining the mass.) Write this value in the observation chart.
7. Fill a 50 mL graduated cylinder with 30 mL of water.
8. Carefully add the cylindrical object to the graduated cylinder. Record the new volume of water in mL in your
observation chart.
9. Repeat steps 5-8 with two other cylindrical objects.
10. Dry your objects and clean your workstation.
Observations:
Part A - Determining Density by Measuring the Volume of Metal Cubes
Cube
Width of Length of Height of
Qualitative Observations
#
Cube (cm) Cube (cm) Cube (cm)
Part B – Determining Density by Water Displacement
Cylinder
Qualitative Observations
#
Mass of
Cylinder (g)
Initial
Volume (mL)
Mass of
Cube (g)
Final Volume
(mL)
Data Analysis:
Use a separate piece of paper to answer the following questions. Show all of your work.
1. Use the data collected in Part A to calculate:
a) The volume of each of the cubes with units.
b) The density of each of the cubes with units.
2. Use the data collected in Part B to calculate:
a) The volume of water displaced with units.
b) The density of each of the cylinders with units.
Conclusion:
Use a separate piece of paper to answer the following questions.
Use the density reference charts and your qualitative observations to identify the metal your cubes and the type
of material that makes up each of the cylinders you tested. (Answer this question in paragraph form.)
Density
(g/cm3
or g/mL)
Density Chart
Density
Substance (g/cm3
or g/mL)
Aluminum (Al)
2.8
Rubber
Zinc (Zn)
7.0
Iron (Fe)
Substance
Density
(g/cm3
or g/mL)
1.5
Delrin
1.4
Acrylic
1.2
PVC
2.1
7.9
Glass
2.2
Oak
0.6
Brass (Br)
8.3
Teflon
1.4
Pine
0.5
Copper (Cu)
9.1
Nylon
1.1
Lead (Pb)
11.6
Substance