Name
What’s In A Penny? LAB #4
Introduction: Prior to 1982, all pennies were made of copper. The United States
government changed the composition of the penny at this time because of an
increase in the price of copper. By comparing the densities of pennies minted
before 1982 and after 1983, we will demonstrate that the composition of these
pennies is different.
Purpose: In this lab, you will calculate the density of sets of pennies minted before
1982 and after 1983 to identify which metals they contain
Necessary Formulas to Remember:
Density = Mass/Volume
Average = sum of values/number trials
Materials: pre-1982 and post-1983 pennies, a 50 mL graduated cylinder, a beaker
of water, a triple-beam balance and your calculator
Experimental Procedure:
1. Pick out at least 15 pennies with dates before 1982 and use your mass and
volume by displacement measuring skills and knowledge of density to fill out the
table below:
Pre-1982 Pennies
Number of
pennies
used
Trial 1
5
Trial 2
10
Trial 3
AVERAGE
DENSITY
15
Mass of
pennies
used (g)
Original
Volume
(you can
use a
convenient
marking)
Volume
after set
of pennies
was added
Volume of
Pennies
Used (mL)
Denisty of
Pennies
(mass (g) /
volume mL)
Part 2: Pick out at least 15 pennies with dates after 1983 and use your mass and
volume by displacement measuring skills and knowledge of density to fill out the
table below:
Post-1983 Pennies
Number of
pennies
used
Trial 1
5
Trial 2
10
Trial 3
15
Mass of
pennies
used (g)
Original
Volume
(you can
use a
convenient
marking)
Volume
after set
of pennies
was added
Volume of
Pennies
Used (mL)
Average Density
Conclusion Questions:
1. Should the volume of increasing numbers of pennies used in the trials
(circle the correct answer) a) increase b) decrease or c) remain the same
In at least 1 complete sentence, explain your logic:
2) Should the mass of increasing numbers of pennies used in trials
(circle the correct answer) a) increase b) decrease or c) remain the same
In at least 1 complete sentence, explain your logic:
3) Should the density of increasing numbers of pennies used in trials
(circle the correct answer) a) increase b) decrease or c) remain the same
In at least 1 complete sentence, explain your logic:
Denisty of
Pennies
(mass (g) /
volume mL)
4) Examine your data carefully in order to answer the following questions:
a) For pre-1982 pennies, were your calculated densities for trials 1-3 similar?_____
b) For post-1983 set pennies, were your calculated densities similar?_____
c) Which of the sets of pennies had a higher density?_____
Have your group reader read the introduction one more time to inform your
discussions about the following questions!
5) Explain why the two sets of pennies should have difference densities
6) Assuming that pennies minted before and after 1982/1983 are the same volume,
explain which set should be heavier and why?
Compare your calculated densities to the densities of the following metals:
Symbol
Element/Metal
Density in
g/mL
Ni
Al
Fe
Zn
Cu
Hg
Pb
Nickel
Aluminum
Iron
Zinc
Copper
Mercury
Lead
8.9
2.7
7.9
7.1
9.0
13.5
11.5
7) Which metal(s) best match your calculated post-1983 density?
8) EXTRA CREDIT!!!!: Find and record the latest market prices of nickel, aluminum,
copper, zinc, iron, silver and gold (be careful that you are comparing prices with the
same units). Explain in at least 2 full sentences why our coins’ composition changes
depending on the global metal market:
Name:
Lab #5, Graphing, What’s in a Penny?
Introduction: Graphs are used to visually illustrate data. You will be graphing your
3 data points for the pre-1982 and post-1983 penny sets, placing volume on the xaxis and mass on the y-axis
Drawing a best-fit line between graphed points is a graphical way in which to
average data. The slope of a best-fit line is equal to the rise divided by the run, as
illustrated in the following formula:
Slope =
rise
run
=∆y
∆x
= y2 –y1
= x2-x1
In this lab your slope should equal your average difference in mass, divided by your
average difference in volume, or the density of the set of pennies!
Purpose: In this lab, we are going to graph the data you collected in Lab #4 and
calculate the slope of the lines illustrating each set of pennies to check your
average density calculations.
Materials: graph paper, pencil, Lab #4, ruler
Procedure (ALL GROUP MEMBERS MUST COMPLETE EACH STEP BEFORE GOING
ONTO THE NEXT!):
1. Draw and label your x and y axis
2. Determine the scale/units to use (the trick is to count the number of lines
on your graph paper and divide it by the range of your data)
3. Mark the lines/units on the axis
4. Locate/identify the data for the pre-1982 pennies on Lab #4 and plot them
with 3 dots
5. Locate/identify the data for the post-1983 pennies on Lab #4 and plot them
with 3 stars
6. Using your ruler, draw the line that best intersects/divides data points and
crosses the (0,0) for the pre-1982 data set
7. Using your ruler, draw the line that best intersects/divides data points and
crosses the (0,0) for the pre-1982 data set
8. Mark two points ON your pre-1982 line and write their x and y values beside
them (format (x,y)
9. Mark two points ON your post-1983 line and write their x and y values
beside them
10. Use the space below to calculate your slope:
Pre-1982 Pennies
Slope =
rise
run
=∆y
∆x
= y2 –y1 =
x2-x1
–
-
=∆y
∆x
= y2 –y1 =
x2-x1
–
-
_ =
Post-1983 Pennies
Slope =
rise
run
_ =
Conclusion Questions:
1. Compare the slopes that you just calculated to your average density values
for each set of pennies. Explain why these values could be different.
2. Explain some of the benefits you discovered to graphing data: