chem 112 lab write up #1 - Forest Swanson Chemistry 112...

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Forest SwansonChemistry 112 Section 015January 29, 2016Colorimetric Determination of copper in a pennyA). Research questions -1. If a substance does not have a color of its own how may one seek to find a chemical reagent that will react with the colorless substance to yield a copper product? 2. What characteristics of a substance may be used to qualitatively detectits presence? B) The year of the penny is 2000 and the mass of the penny is 2.509C) The percent copper in our penny was 2.5%D) Me and my partner Lucas established the dependence of the absorbance (intensity of color) on the concentration of Cu(NH3)4^2+ complex by creating a standard calibration curve. Then we converted the copper to this same Cu(NH3)4^2+ complex, we measured its absorbance and used this data to determine the % copper in the penny.E) Reflection-The concentration of ammonia will matter, but only up to a certain point.When you dissolve copper in nitric acid, you form copper nitrate, which is very soluble, but as you say, not very absorptive.

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