html5-img
1 / 17

The Composition of Pennies Pre-1982 and Post-1982

The Composition of Pennies Pre-1982 and Post-1982. Tim Cumming & Caitlin Carmody. Timeline of the Penny. Composition pure Copper from 1793 to 1837 From 1837 to 1857, 95 % Cu, 5 % Sn and Zn In 1857, 88 % Cu, 12 % Ni 1864 to 1962, 95 % Cu, 5 % Sn and Zn In 1962, 95 % Cu and 5 % Zn

awena
Télécharger la présentation

The Composition of Pennies Pre-1982 and Post-1982

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Composition of Pennies Pre-1982 and Post-1982 Tim Cumming & Caitlin Carmody

  2. Timeline of the Penny • Composition pure Copper from 1793 to 1837 • From 1837 to 1857, 95 % Cu, 5 % Sn and Zn • In 1857, 88 % Cu, 12 % Ni • 1864 to 1962, 95 % Cu, 5 % Sn and Zn • In 1962, 95 % Cu and 5 % Zn • In 1982, 97.5 % Zn and 2.5 % Cu

  3. Why did the composition change? • The value of Copper increased (almost double) making the government lose money when they produced pennies • Zinc was, and still is, the most economical element to make the coin

  4. Objectives • Use AA and ICP to determine the amount of Copper in pennies from post and pre-1982 • Compare our results to the expected values of 95 % Copper for pre-1982 and 2.5 % for post-1982 • Also compare that to the amount of Copper in dimes within the same time periods, to see if the Copper changes occurred in them too

  5. Method • Weighed out 20 coins (10 of each type) to determine theoretical concentration of Cu • Dissolved 16 coins (8 of each type) in HNO3 (12 mL, 15 M, 48 h) • Made standards to correspond to theoretical concentration of Cu • Diluted samples with distilled water • Ran samples through AA and ICP • Analyzed data provided

  6. Coin Data

  7. AA Standards

  8. AA Samples

  9. Percent Error

  10. ICP Standards Concentration=0.0021(int)-0.3502 Concentration=0.00005(int)-0.5964

  11. ICP Samples Concentration=0.0021(int)-0.1795 Concentration=0.00005(int)-0.0522

  12. Percent Error

  13. Results • The overall trend followed with our idea that as mass increased, the Copper content would increase • Also supported the theory that the composition changed over the years, specifically from pre- to post-1982 • It is obvious that the samples were much higher than the standards prepared, at least with the AA • The ICP, being the ever-temperamental piece of equipment that it is, gave the exact opposite results that the AA produced

  14. Conclusions • It is inconclusive based on the data we obtained as per the percentage of Cu in dimes and pennies • Due to the many reasons on the next slide…

  15. Problems • Our standards did not match up to where we believed that our samples would be • The ICP seems to have changed its mind on the reading it gave for a blank sample of distilled water between the dates of 24/4 and 29/4 • We believe that we added to the burning of the torch head of the ICP, and we are sorry for that, but if it is any consolation, we didn’t get any reliable results, so it got us back, immediately

  16. Sources • http://www.usmint.gov/about_the_mint/fun_facts/index.cfm?flash=no&action=fun_facts2 • http://www.scholieren.com/proef/35020

  17. Questions?

More Related