Sample Traditional Lab Report - Density of Pennies
Hypothesis (Based on the instructions provided)
The density of pennies made before 1982 will be greater than the density
of pennies made after 1982.
Data
Table 1
Trial
1
2
3
Mass of 10 pennies made
before 1982
123.08 g
123.07 g
123.07 g
Mass of 10 pennies made
after 1982
101.42 g
101.43 g
101.43 g
Table 2
Trial
1
2
3
Volume of water
and 10 pennies
made before 1982
59.0 mL
66.5 mL
68.0 mL
Volume of water
Volume of water
and 10 pennies
made after 1982
65.0 mL
68.0 mL
65.0 mL
Volume of water
45.0 mL
52.5 mL
54.0 mL
Volume of 10
pennies made
before 1982
14.0 mL
14.0 mL
14.0 mL
Table 3
Trial
1
2
3
51.0 mL
53.0 mL
50.0 mL
Volume of 10
pennies made
after 1982
14.0 mL
15.0 mL
15.0 mL
Analysis
Calculations:
1.
Calculate the average mass of the 10 pennies made before 1982.
123.08 g  123.07 g  123.07 g   123.07 g
3
2.
Calculate the average mass of the 10 pennies made after 1982.
101.42 g  101.43 g  101.43 g   101.43 g
3
3.
Calculate the average volume of the pennies made before 1982.
14.0 mL  14.0 mL  14.0 mL   14.0 mL
3
4.
Calculate the average volume of the pennies made after 1982.
14.0 mL  15.0 mL  15.0 mL   14.7 mL
3
5.
Calculate the density of the pennies made before 1982.
123.07 g
g
 8.79
14.0 mL
mL
6.
Calculate the density of the pennies made after 1982.
101.43 g
g
 6.90
14.7 mL
mL
Questions:
1.
Why is it best to use the results of three trials rather than a single trial
for determining density?
Conducting more than one measurement reduces the effect of
measurement errors.
2.
How did the densities of the two groups of pennies compare? How do
you account for any difference?
The pennies made after 1982 were less dense. The volumes of the two
groups were close to each other, but the masses had a larger difference.
It looks like the pennies made after 1982 contain a different material.
3.
Given that the density of copper is 8.92 g/mL, use the results of this
experiment to formulate a hypothesis about the composition of the two
groups of pennies. How could you test your hypothesis?
The density of the pennies made before 1982 was very close to that of
copper. Copper may have been replaced with another lighter metal.
We could check the density of the second group of pennies against the
densities of known metals to see what the replacement metal is.
Error Statement
A green residue on some of the pennies may have affected the mass
measurement.
Some water splashed out of the graduated cylinder on the second
trial of the pennies made after 1982, which affected the volume
measurement.
Water retained by the pennies may have increased the volume
measurements.
Conclusions
The density of pennies made before 1982 was measured to be 8.79 g/mL,
while the density of pennies made after 1982 was measured at 6.90 g/mL. This
confirms our hypothesis stating that the pre-1982 pennies would be more dense.
It is believed that a change in the composition of pennies was made in 1982 to
make them lighter.
Lab Report Requirements
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All lab reports must be written by hand in a bound lab notebook.
Reports will not be graded if they are not turned in the lab
notebook.
Lab notebooks should only have lab reports in them.
All lab reports must be written in pen. First offense is a warning.
Subsequent offenses will incur a 10 point penalty.
Each lab report must have the sections listed in the sample report
unless otherwise directed in the lab instructions.
Late Penalty: 10 points for each day late. (All lab reports are 50
points)
Other Lab Procedures
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Some report requirements or lab instructions may be waived at my
discretion. These changes will be announced prior to the start of
the lab.
Lab instructions will go out to you at least one day before a lab is
scheduled.
Due dates for lab reports will be announced on the final day of a
lab activity.
If you are absent on a lab day, you must make arrangements to
make up the lab as soon as possible.
o Your due date is based on when you make up the lab.
o Most labs will be made up in class, usually on a review day.
Making up labs after school or during other periods are
possible, but they are subject to my availability. No labs will be
made up during sixth period (my lunch period).
Cheating on lab reports can be defined as including, but not limited
to the following actions.
o Passing off data generated by others as your own
o Plagiarizing answers of questions from other students
o Making up data without doing the experiments
Any student caught cheating on a lab report will receive a
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student code of conduct.