Melting Penny Lab

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

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

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 2.4375 grams

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

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

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

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

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

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

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

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

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!