Tuesday, Sept. 10th: “A” Day
Wednesday, Sept. 11th: “B” Day
Agenda
Check lab write-ups
Lab: “Counterfeit Pennies”
Discussion/Safety/Questions
Conduct Lab
Calculations/Graph/Conclusions
Homework: Complete lab, due next time…
Lab: “Counterfeit Pennies”
Discussion
The pennies are on the back supply table in
plastic cups that are separated by year.
There are 42 cups of pennies, so each group
will test 3 or more different years. Test 1 year
at a time!
You will use a balance and a graduated
cylinder to determine the density of pennies.
When done, make sure to DRY OFF
pennies and put back in the correct cup
for the next class.
Lab: “Counterfeit Pennies”
Discussion
 Be careful when measuring the volume of
water in the graduated cylinder. Be as precise
as possible for the best results. Use a squirt
water bottle to get exactly the volume you
want.
 Find the density by dividing the mass of the
total pennies used (g) by the change in volume
(mL).
Density = mass (g)
change in volume (mL)
Lab Write-Up: “Counterfeit Pennies”
After your reflection statement, include a data
table that looks like this:
Data Table #1
Year
Total Mass Volume
Total
Change Density
of Pennies of Water Volume
in
(g/mL)
Used
to Start of Water Volume
(g)
(mL)
+ Pennies of Water
(mL)
(mL)
Lab: “Counterfeit Pennies”
Analysis
After conducting the lab, the whole class will
compile their data to create another table:
Year
Density
Note: you
(g/mL)
will need a
lot more
lines than
shown
here…
Lab: “Counterfeit Pennies”
Analysis
As part of your analysis, you will construct a
graph with year on the x-axis and density on
the y-axis using the data table created by the
whole class.
Title of Graph
Density
(g/mL)
Year
From this graph, you should be able to
determine the year that the pennies changed
composition.
Lab Write-Up: “Counterfeit Pennies”
Conclusion Questions
(Complete Sentences!)
1. What measurements are necessary to determine density?
2. Based you your graph, in what year did the counterfeit coins
appear?
3. Using Table A-5 in the back of your textbook (pg 829-830),
hypothesize which metal was used in the counterfeit coins.
4. How would mass measurements be affected if the pennies
were still wet from volume measurements?
5. What do you think is the biggest source of error in this
experiment? How could you minimize these errors in future
trials?
Lab: “Counterfeit Pennies”
Safety Items
Even though you will only be using water, you
still need safety glasses and aprons in the lab.
Be careful with the graduated cylinders; they
are glass and will break if knocked over.
Never put anything directly on the balance
pan; use the plastic weigh boat.
Be safe and have fun in the lab!
Lab: “Counterfeit Pennies”
When finished, staple graph behind lab
handout and put behind the “Lab Techniques”
lab in the right-hand side of your lab folder.
Completed lab will be due next class period…
We will finish chapter 1 and cover section 1.3
next time…