Introduction: The purpose of this experiment is to analyze the efficiency and accuracy of determining the mass composition of copper in a penny using two methods: atomic absorption spectroscopy and ultraviolet-visible spectroscopy. The “Copper” PennyThe penny is a common form of currency used in the United States, having the monetary value of one cent. From 1793 to 1837, the one cent coin was made of pure copper. Over the years, the percentage composition of copper in a penny has decreased. From 1837 to 1857, the penny was made of bronze; containing 95% copper and 5% zinc and tin. In 1857 it was 88% copper and 12% nickel for a brief period then reverted to bronze until 1962, with the exception in 1943 when it was zinc plated steel due to the demand for copper for the war effort. In 1962, the tin was removed, making the penny 95% copper and 5% zinc until 1982 when the composition was drastically changed to 97.5% zinc and only 2.5 % copper, commonly called copper zinc. In this experiment we will analyze the use of atomic absorption and ultraviolet-visible spectroscopy to determine the mass composition of copper in pennies before and after the sea change of 1982. Atomic absorption spectroscopyAtomic absorption spectroscopy is a technique used to identify the presence and concentration of substances by analyzing the spectrum produced when the substance is vaporized and absorbs certain frequencies of light. In atomic absorption spectroscopy, the sample is broken down into atoms by a heat source, such as a flame. The flame not only atomizes the sample, but also removes the solvent used to dissolve the compound so we can analyze only the desired atoms. The concentration of atoms in the vapor is measured by the absorption of...... middle of paper ...... Mint 1997-2014, nd Web. January 26, 2014. Harris, Daniel C. Quantitative chemical analysis. 8th ed. New York: WH Freeman, 1999. “How AAS Works” in print. YouTube. Vic Space Sci Education Centre, May 1, 2011. Web. January 26, 2014. "Atomic Absorption Spectroscopy (AAS) -." EasyChem. Np, and Web. January 26, 2014. “Ultraviolet/visible (UV-Vis) spectroscopy.” » YouTube. Royal Society of Chemistry, September 28, 2008. Web. January 26, 2014. .Gallik, Stephen. “Spectrophotometry: transmission and absorbance.” OLM cell biology. Np, and Web. January 26. 2014. .