Design a Lab
The Composition of Pennies
BHS Lab Format
You will use the BHS lab format for most of
your labs in this class.
Where is this found?
You will also use the rubric to create an
excellent final report!
- You have used this for 2 years now….
Background
U.S. pennies have been composed of copper
and zinc since 1959 but the ratio of copper to
zinc has changed due to an increase of
copper prices.
Copper and zinc are both metallic elements
and they share many physical properties but
have different densities.
Density of copper is 9.0 g/mL
Density of zinc is 7.1 g/mL
Background (cont)
Because of these density differences it is
possible to track the changes in the
composition of the penny.
Your Task:
Your job is to create and execute a lab procedure to
figure out when the composition of the penny
changed.
1st design the procedure using the BHS lab format and
densities. This must be completed before the lab
can be performed tomorrow. DUE today.
2nd execute the procedure and gather data
Wednesday. DUE Wednesday
3rd The entire lab which includes a PEA conclusion
(group effort)and analysis questions will be DUE on
Friday.
Further information
 This
lab must use a non destructive method. You
can’t destroy the pennies.
 You can (but may not need to) use the following
equipment:
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Balance
Beakers
Graduated cylinder
Funnel
Forceps
Test tubes
Water
You have 20 minutes to come up with a procedure!
Further Information (cont)
I
will give you 10 pennies.
 Use the density equation to help you.
 Use the BHS lab format to shape your
procedure and final report
 Key
point…How can I get the volume of
an “odd” shaped item???
 What equation is needed to calculate
density?
Title: Penny Composition
Problem, CH 1
Objectives:
1)To measure mass and volume, and
calculate the density of a variety of
pennies.
2)To determine approximately when
the composition of the pennies changed.
Procedure:
1) Record the mint date of each penny (10)
in the data table.
2) Using the balance measure the mass (g)
of each penny (10) and record.
3) Measure 15.0 mL of tap water in a
graduated cylinder. Record the volume to
the nearest 0.1 mL.
4) Add each penny to the water in the
cylinder carefully. Tap out any air bubbles.
Procedure (cont)
5) Measure the new volume of the water to the
nearest 0.1 mL
6) Calculate the difference between initial and
final volume
7) Divide the difference by the total number of
pennies (10). This is the
AVERAGE volume of
one penny
8) Calculate the density of each penny by
dividing the individual mass by the average
volume.
9) Record these calculations in the data table.
Questions:
1)
Approximate the year that the United
States Mint changed the composition of
the penny.
2) What is the theoretical density of
copper? Zinc? Use the CRC as your
resource.
Questions (cont)
3) Why might your density data be slightly
different from the theoretical data? Why
might your data be different from another
group? How could we improve our results?
4) How would you determine the density of
a similarly shaped solid object that was
soluble in water?
5)If the density of iron is 7.86 g/mL, how
many grams are there in 5.0 mL of iron
metal? Use dimensional analysis to
determine your answer.