Lab_Report_2 - Experiment 2 Chemical Compositions of...

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Experiment 2: Chemical Compositions of Pennies Lida Niake and Kayla Saravia 50 % and 50% Chemistry 125 Section D California Baptist University
Introduction: The composition of one cent coin (penny) has been changed several times. In this experiment, pre-1983 and post-1984 pennies consist of copper and zinc however the mass percent of copper and zinc are different. Our objective is to devise an experiment to determine the mass percentages of copper and zinc for both pre-1983 and post-1984 pennies by using Beer- Lambert Law and PASCO Spectrometer system. In order to determine the mass percent of copper and zinc in pennies, we will need to dissolve penny samples in concentrated nitric acid solution. The blue-ish color of the solution is due to dissolved copper (Cu+ ions). Zinc will likely dissolve in nitric acid, however Zn2+ is transparent and does not absorb visible spectrum. According to the Beer-Lambert Law, the amount of light absorbed by lighting chemicals such as Cu2+ is directly proportional to the concentration (molarity).

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