Formal Report Penny - Devon Wing Professor Bretz Experiment...

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Devon WingProfessor BretzExperiment 811/10/2014Lab Partners: Hannah Woods & Chelsea GanttHow Much Copper is in a Penny?
dissolved penny solution in order to form the complex ion Cu(NH3)4 2+ which will beused to determine concentration.Cu(H2O)4 2+ (aq) + 4NH3 (aq)  Cu(NH3)4 2+ (aq) + 4H2O (l)Zn(H2O)4 2+ (aq) + 4NH3 (aq)  Cu(NH3)4 2+ (aq) + 4H2O (l)This study is performed in order to determine the concentration of Copper in agiven penny.This reason for the being is that in the 1980s, the price of copper rose to thepoint where the price of copper in the penny cost more than the face value of the coin.With this being said, in 1982 congress authorized a percentage of copper in penny to be2.5% by mass.Therefore, the penny now is primarily composed of Zinc and has a coppercovering. To determine the concentration of copper in a penny, it is vital to becomefamiliar with the Beer-Lambert Law, which states that absorbance is directly proportionalto concentration.A=abc(A=absorbance, a=absorptivity of absorbing substance, b=units ofabsorptivity, c= concentration)To determine absorbance, a UV-visible spectrophotometer will be used.Thismeasures how much light energy of a particular wavelength, is absorbed.Thespectrophotometer will measure the known solutions containing Cu(NH3)4 2+ toestablish a liner curve. From here, the unknown concentration of Copper obtained fromthe penny will be measured using interpolation.The Hypothesis of this experiment, with there being a mandate restricting penniesto have a copper percentage of 2.5% or less, the pennies that are tested should be under2.5%.

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Term
Fall
Professor
Riechel
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