Tuesday, Sept. 10th: “A” DayWednesday, Sept. 11th: “B” Day

AgendaCheck lab write-upsLab: “Counterfeit Pennies”

Discussion/Safety/QuestionsConduct LabCalculations/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 of Pennies

Used(g)

Volume of Water to Start

(mL)

Total Volume

of Water + Pennies

(mL)

Change in

Volume of Water

(mL)

Density (g/mL)

Lab: “Counterfeit Pennies” Analysis

After conducting the lab, the whole class will compile their data to create another table:

Year Density (g/mL)

Note: you will need a lot more lines than shown here…

Lab: “Counterfeit Pennies” AnalysisAs 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

From this graph, you should be able to determine the year that the pennies changed composition.

Density (g/mL)

Year

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…