Introduction: The purpose of this experiment is to analyze the effectiveness and accuracy in determining the mass composition of copper in a coin 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, with the monetary value of one cent. From 1793 to 1837 the penny was made of pure copper. As the years passed, the percentage composition of copper in the coin decreased. From 1837 to 1857 the penny was bronze; containing 95% copper and 5% zinc and tin. In 1857 it was 88% copper and 12% nickel for a short time then back to bronze until 1962, with the exception of 1943 when it was galvanized steel due to the demand for copper for the war effort. In 1962, the tin was removed making the penny composed of 95% copper and 5% zinc until 1982, when the composition was drastically changed to 97.5% zinc and only 2.5% copper, commonly known as coppered zinc. In this experiment we will investigate the use of atomic absorption and ultraviolet-visible spectroscopy to determine the mass composition of penny copper before and after the dramatic change in 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 eliminates the solvent used to dissolve the compound so that only the desired atoms can be analyzed. The concentration of atoms in the vapor is measured by the absorption of the...... middle of paper...... Mint 1997-2014, nd Web. January 26, 2014. Harris, Daniel C. Quantitative chemical analysis. 8th ed. New York: WH Freeman, 1999. Print."How AAS Works." YouTube. Vic Space Sci Education Centre, 1 May 2011. Web. 26 January 2014. ."Atomic Absorption Spectroscopy (AAS) -." EasyChem. Np, nd Web. January 26, 2014. “Ultraviolet/Visible (UV-Vis) Spectroscopy.” YouTube. Royal Society of Chemistry, 28 September 2008. Web. 26 January 2014. Gallik, Stephen. "Spectrophotometry: transmittance and absorbance." Cell Biology OLM. Np, nd Web. January 26. 2014. .