1. Melting Penny Lab

2. Problem:
What percentage of Zinc can safely be removed from a post-1983 penny?

3. Previous Knowledge: Pre-1983 (1962) Penny Post-1983 Penny
95% Cu and 5% Zn
Post-1983 Penny
97.5% Zn and 2.5% Cu
Mass = 2.50 grams
Melting Points
Zn = 420 °C
Cu = 1084 °C

4. Hypothesis:
Not needed – however, you can estimate how much zinc can be removed based on mass and percentages.
Therefore, a penny that masses at 2.50 grams would have what mass of Zn?
97.5% of 2.50𝑔 is 𝑥
grams

5. Materials:
Post 1983 Penny
Bunsen Burner
Beaker of Water
Metal Tongs

6. Procedure: Gather materials
Mass the Penny, note the date, and make any other pertinent observations about the penny
Start Bunsen Burner
Hold the Penny with Metal Tongs and slowly move the Penny around just above the hot blue cone in the middle of the Bunsen Burner, move the entire penny through the blue cone to melt all the zinc
After several seconds check to see if the Zinc is ready to ooze out
If Zinc does not ooze out, continue to heat for 5 seconds intervals – Do not melt the copper
Tap Zinc out into Petri dish of water
Once Zinc is out, bend the Penny so it will stand on its own and then place in the water to cool
Mass the Copper Shell
Mass the Zinc

7. What you need to do: Identify Data & Results – Make a Table
Year of the Penny
Mass of the Penny at the start
Expected Mass of Cu Shell and Zn
Expected Percentage of the Penny
Measured Mass of Cu Shell and Zn Removed
Measure Percentage of the Penny
Create Two Pie Charts

8. Expected Results 2.5% * Mass of Penny = Mass of Cu Shell
97.5% * Mass of Penny = Mass of Zn

9. Measured Results Mass of Cu Shell ÷ Mass of Penny * 100 = % of Penny
Mass of Zn ÷ Mass of Penny * 100 = % of Penny

11. Results: Create a Pie Graph Expected Mass of Copper Shell and Zinc (%)
Measured Mass of Copper Shell and Zinc (%)
Title, Color, Legend

12. Results: To convert Expected and Measured % into degrees on a circle
2.5% (360 degrees) = 9 degrees
97.5% (360 degrees) = 251 degrees
Measured
21.03% (360 degrees) = 76 degrees
78.57% (360 degrees) = 283 degrees

13. Notes:
If your measured percentages add up to LESS THAN 100%, then you will have a third slice of pie listed as Lost Material
If your measured percentages add up to EXACTLY 100%, then you will only have the two slices of pie

14. Notes:
If your measured percentages add up to MORE THAN 100%, then you will need to do the following:
Example numbers
Cu Shell = 27%
Zn = 81%
Total = 108%
Divide each percentage by 1.08 (do you see where that number came from? If your total was 125% you divide by 1.25 and so on.)
Cu Shell = 27% ÷ 1.08 = 25%
Zn = 81% ÷ 1.08 = 75%
These are the new percentages you use to create your Pie Chart!