 # Lab:        Money Trouble – Determining Density of Pennies

1.      Conduct experiment to analyzing the density of pennies.

2.      Clearly state the problem you are going to investigate for all three parts; A, B, and C.  Remember to include a clear identification of the independent and dependent variables that will be studied.

3.      Take notes on this handout.  Each student is responsible for completing a formal lab report.

4.      Complete a typed, formal lab report following the guidelines in the handout entitled “Lab Report Format”.  Tables, charts and/or graphs should be used where appropriate.  Do not just use your notes on this handout!  For this lab, NO COMPUTER GENERATED GRAPHS.

5.      Answer the Analysis and Conclusions Questions, and include them in you lab report.

## Materials Triple beam balance 100 ml graduated cylinders Paper clips Pennies Water Reference materials to explore the minting of coins and density of metals

## Procedure

Part A:

1.      Determine mass of 5 paper clips,  then 10 paper clips, then 15 paper clips, then 20 paper clips.

2.      Determine the mass of 5 pennies, then 10 pennies, then 15 pennies, then 20 pennies.

3.      Record your data on the table on page 2.

4.      Graph graph both sets of data you gathered on the paper clips and pennies.  Note any differences.

Part B: Pre-1982 Pennies

5.      If using glass graduated cyclinders - Put on your safety goggles!  Pour 30 to 40 mL of water into a 100 mL graduated cylinder.  Record the volume of the water in the cylinder on the data table on page 2.  Leave the water in the cylinder.

6.      Using the balance, determine and record the mass of four (4) pre-1982 pennies.

7.      Slide the four pre-1982 pennies into the graduated cylinder, being careful not to splash any water.  Record the volume of the water plus pennies.

8.      Subtract the original volume to determine the amount by which the volume changed when you added the five pennies.  Record this amount as the volume of the four pre-1982 pennies.  This is known as displacement volume.

9.      Use the formula D=m / V to determine the density of the four pennies.  Record the density.

10. Take four more pre-1982 pennies, and determine their mass.  Add this mass to the mass in step #6.

11. Add these 4 additional pennies to the graduated cylinder carefully, and determine the displacement volume. Repeat steps 8-9.

12. Take four more pre-1982 pennies; and repeat steps 10-11 for a total of 12 pennies.

13. Remove the pennies and the water from the graduated cylinder, and dry them off for storage.

Part C:  Post-1982 Pennies

1.      Repeat steps 5-13 using post-1982 pennies.

2.      Plot the data for the mass and volume of the pre-1982 pennies and post-1982 pennies on a graph.  Draw a straight line on the graph that come as close as possible to most of the points.

Analysis and Conclusions:

1.      Describe the graph of the paper clips.

2.      Was the first graph of the pennies, weighed in step two similar?  Explain.

3.      From your graph, what is the difference between the pre- and post-1982 pennies?

4.      Research the minting of pennies, and explain the difference you found through experimentation.

5.      On the last graph, draw and label a line for the density of copper. (You need to research the density of copper.   Remember to use metric units).

6.      On the last graph, draw and label a line for the density of zinc.

 Paper Clips Mass (g) Pennies Mass (g) 5 5 10 10 15 15 20 20

Data Table for Pre-1982 Pennies

 Quantity Mass of pennies (g) Starting volume in cylinder (mL) Volume of water and pennies (mL) Volume of pennies (mL) Density of pennies (g/mL) 4 8 12

Data Table  for Post-1982 Pennies

 Quantity Mass of pennies (g) Starting volume in cylinder (mL) Volume of water and pennies (mL) Volume of pennies (mL) Density of pennies (g/mL) 4 8 12

HINT FOR GRAPHING….

THE VOLUME (mL) is on the X axis, and the MASS (g) is on the Y axis, because the formula is Density = mass/volume