CHEMISTRY I
Mass, Volume, and Density
BACKGROUND: An old riddle asks “Which is heavier, a pound of feathers or a pound of
lead?” The question is nonsensical of course, since a pound of feathers and a pound of lead
both weigh the same thing, one pound. Nevertheless, there is clearly something different
about a small lead brick and a large bag of feathers, even though they weigh the same. The
key to answering the riddle is in understanding the relationship that exists between a
substance’s mass and the volume it occupies. This relationship is expressed by the physical
property called density. Density is defined as the ratio of a substance’s mass to the volume
it occupies.
density =
mass of substance (g)
volume of substance (mL)
In this experiment, you will measure the mass and volume of several unknown materials. You
will then use your data to explore the relationship between the mass and volume of the
materials and to calculate their density.
After performing this lab if someone asks you the riddle about feathers and lead, you can
explain to them the difference between weight and density.
Safety:
 Always wear safety goggles and a lab apron to protect your eyes and clothing.
 Always clean up the lab and all equipment after use. Return all equipment to its proper
location. Wash your hands thoroughly before leaving the lab.
Materials and Procedure:

25 mL graduated cylinder

3 unknown metal samples per group

ruler

graph paper
Procedure:
1) Obtain clean, dry samples of three different metals. Write down the description of each.
2) Measure the mass of each metal to the nearest 0.01 g. Record in Data Table 1.
3) Measure the volume of each metal separately using the displacement method:
a) Fill a graduated cylinder halfway with sink water. Tap out any air bubbles.
Record the initial volume to 0.1 mL in Data Table 1.
b) Tilt the cylinder gently and slide the metal into it. (It must be submerged.)
Tap out any air bubbles. Record the final volume to 0.1 mL in Data Table 1.
4) When finished, carefully pour out the water and metal into your hand.
Dry the metal samples and give them to the teacher.
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CHEMISTRY I
Mass, Volume, and Density
For your Pre-Lab write-up, include (On the left hand page of your spiral):
Title, Purpose, Procedure, and 2 Data Tables
As you perform the experiment, record your data in Tables 1-#2,3a,3b. The other data
will be filled in afterwards.
Table 1 - Individual Data and Calculations
Metal A
Metal B
Metal C
(2.) Mass (g)
(3a.) Volume of water alone (mL)
(3b.) Volume of water+metal (mL)
(5.) Volume of metal (mL)
(6.) Density (g/mL)
Posted in class- Class Data:
Mass and Volume of Metal Samples
Metal A
Lab
Mass (g) Volume (mL)
Group
1
2
3
4
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Metal B
Mass (g)
Volume (mL)
2
Metal C
Mass (g)
Volume (mL)
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CHEMISTRY I
Mass, Volume, and Density
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6
7
Averages
Table 3 - Density Calculations from Class Data
Metal A
Metal B
g/mL
Metal C
g/mL
g/mL
CLEANUP AND DISPOSAL
2. Clean up your equipment and lab station. Thoroughly wash your hands after completing
the lab work and cleanup.
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CHEMISTRY I
Mass, Volume, and Density
Post Lab Write-up – Record the analysis on the right hand page.
DATA ANALYSIS
Calculations
5) Calculate the volume of each of the metals you tested.
VOLUME of metal = (FINAL VOLUME) – (INITIAL VOLUME) in mL
6) Calculate the density of each metal by DENSITY = MASS / VOLUME. Use the proper
units and sig.figs.
 Record your lab group information in Table 1.
7) Complete Table 2 by recording the mass and volume data collected by you and your
classmates. Calculate class averages and class density
 Record class average on Table 2 and class density on Table 3.
Graph - Class data using graph paper
8) Choose a different color for each of your unknown metals for your graph.
Using the class data, plot a graph of mass versus volume. Represent the plotted
points for each metal with a different symbol or color. Draw a “best fit” straight
line through each group of plotted points. X=Volume, Y=Mass
9) Determine the slope of each line by choosing two points directly on the line:
SLOPE = RISE = y2 – y1
RUN
x2 – x1
Copy the table below and fill in the information.
Table 4
Metal A
Metal B
Metal C
Slope of the line
Accepted Value
(from book)
The slope of the line is the density of the metal (M/V).




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Look at the class density in Table 3 of the unknown metals you graphed; this is the
slope of your line. Is your slope calculation close to the density numbers?
Examine your own lab group’s density for the same unknown. This also is the slope.
Using your data, identify the metals.
Record the accepted density, given by the teacher, of the unknown that you graphed.
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CHEMISTRY I
Mass, Volume, and Density
10) Add to calculations section
Calculate two percent errors for each metal (total of 6):
% ERROR OF CLASS = Accepted Value – Experimental Value
Accepted
x 100
% ERROR OF LAB GROUP = Accepted – Group Density x 100
Accepted
Questions
1) What does the slope of the line for each metal represent?
2) What was the unit of mass used in this lab?
3) How many decimal places should the masses have in this lab?
4) What was the unit of volume used in this lab?
5) How many decimal places should the volumes have in this lab?
6) Describe how water displacement works.
7) What is a meniscus?
8) Can density be used as identification for substances in lab? Why or why not?
9) Which was more accurate, your own lab group’s data or the class data?
10) What may have caused experimental errors?
Conclusion:
Look at your hypothesis and your analysis and discuss the results in this section
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