Calorimetry Lab Report

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This experiment was design to find the amount of copper in a penny using a visible spectroscopy. We achieved this by combining .89 to .93 of Cu(NO3)2*2.5H2O to a 25mL volumetric flask and filling the flask to about half full with deionized water, swirl, then fill to the line with more deionized water. After, fill a 25mL burret with Cu2+ stock, with this add .5, 1, 1.5, and 2 mL of the stock to four different volumetric flask, add 2mL of 15 M NH3 from the burret to each flask and swirl, then fill to the line with deionized water. First, calibrate the spectrophotometer then; enter samples of each of the four samples in the spectrophotometer to test the absorbency. For the penny stock solution, use a 500 mL filter flask with about 250 mL of 1 M NaOH, place a rubber stopper to the top and connect a inverted long stem funnel to it using tygon tubing, and place a 125 mL flask below it. Turn on the water aspirator, place the penny in the 125 mL flask, measure out 20-25 mL of 8 M nitric acid in a 50 mL graduated cylinder, and then slowly add it. It should take about 5-10 minutes for the penny to dissolve.…show more content…
The newest penny, 2015, had the lowest average % but there was no other trend observed. When calculating the mass of copper mental in the penny we assumed that the penny was dissolved evenly throughout the solution when calculating the concentration of [Cu(NH3)4]2+. Our measurements of the penny were similar to those set by the United States Mint, we observed that the pennies dated in 2012, 2013, and 2015 all had a thickness of 18.9mm while the ones dated in 2006 and 2000 had a thickness of 18.5mm, but had similar percent by mass of copper as they
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