Density of Pennies - H
Introduction
Prior to 1982, pennies were made from pure copper. But as the cost of copper
rose, it became more expensive to make a penny than the penny was worth. The solution
to the problem was to make the penny from a less expensive metal, but maintain the look
of a penny by adding a thin layer of copper on the outside of the new metal. In this lab
you will examine pennies made before 1982 and those made after that time. You will
collect data and determine the densities of the two types of pennies. From this
information, you should be able to determine the metal found inside of the “new”
pennies.
Hypothesis
Write a hypothesis stating what metal you think is found inside the penny. Include a
brief explanation of why you chose this metal.
Procedure
1. Make two data tables like the ones shown below.
2. Obtain two sets of 25 pennies. One set should all be Pre-1982 and the second set
should all be Post-1982.
3. Using only one set of pennies, measure the mass of 5 pennies and record on your
data table. Add 5 more pennies (10 total) and measure the mass and record.
Repeat this process, adding 5 pennies each time, until the mass of all 25 pennies is
determined.
4. Using the same set of pennies, measure the volume of 5 pennies by displacement
and record on your data table. Repeat as in step 3 until all 25 pennies have been
measured.
5. Repeat steps 3 and 4 using the other set of pennies.
6. Be sure to completely dry your pennies when finished.
Pre-1982
Number of Pennies
5
10
15
20
25
Post-1982
Number of Pennies
5
10
15
20
25
Mass(g)
Volume(ml)
Mass(g)
Volume(ml)
Analysis
1. Do the pennies appear to have equal densities?
2. What does that tell you about the post-1982 pennies?
3. Make a graph of your data. You will have two lines on your graph. One for the
pre-1982 and one for the post-1982 pennies. Place the mass on the Y-axis and the
volume on the X-axis. Plot your points by using the mass and volume
measurements as your points. Draw a best fit line through the points for each set
of data. Color code your lines.
4. The density of each type of penny can be determined by calculating the slope of
each line. Use the following formula to determine slope. Choose two points on
your line to use in the formula.
Slope= Y2 – Y1
X2 – X1
5. Use the provided list of element properties to choose 3 possible candidates for the
metal found inside the post-1982 pennies.
Conclusion
Discuss the lab procedure and your results. Was your original choice one of the three
determined in this lab?
Error
List three sources of error for this lab.
Density of Pennies Lab
Grading Rubric
Name: _____________________
Block: ______________
Component
Title
5 points
Purpose
5 points
Hypothesis
5 points
Procedure
10 points
Data
10 points
Analysis
20 points
Error Analysis
5 points
Conclusion
5 points
Participation
10 points
Total Points
75
Clearly reflects
lab
5 points
Clearly stated
5 points
Present-with
reasons
5 points
Detailed, all
points present,
step by step
10 points
Present,
complete,
neatly done
5 points
Present, all
questions
answered,
graph present
20 points
3 sources of
error identified
5 points
Well written
paragraph,
refers to
data/procedure
5 points
Worked
consistently,
safety gear
10 points
Due Date:_________
Possible Points
Present, but unclear
1-4 points
Present, but unclear
1-4 Points
Present but incomplete
1-4 points
Present, but incomplete or
not clear
1-9 points
Present, but needs work
Points
Absent
0 points
Absent
0 points
Absent
0 points
Absent
0 points
Absent
0 points
1-9 points
Present, but incomplete
Absent
0 Points
1-20 points
1-2 sources identified
Absent
1-4 points
Present, but does not refer
to data/procedure
0 points
Absent
1-4 points
Had to be
reminded to
focus 2-3
times
7-8 points
0 points
No work
Had to e
reminded
to focus 45 times
4-6 points
0 points