100%(1)1 out of 1 people found this document helpful
This preview shows page 3 - 5 out of 7 pages.
charge. After this was done, 6 50mL Volumetric Flasks were gathered in order for Cu2+ Solution to be pipetted into them. These volumetric flask received 0.00mL, 2.00mL, 4.00mL, 6.00mL, 8.00mL, and 10.00mL of solution, respectively. Following this the volumetric flask received 3mL of concentrated ammonia (at 15M) solution, and it was also diluted with distilled water and mixed to create a solution in each volumetric flask. Once mixed, the concentration of Cu2+was calculated and recorded in g/L for each flask. To conclude this step, one plastic cuvette was gathered for the 0.00g/L solution. Then the cuvette was filled to about ¾ of the way with solution.Absorbance MeasurementThe second step, the preparation of the penny samples, required that 3 pennies be gathered from the TA. The three pennies were then weighed and had their mass recorded, along with their condition, and year of production. After this was done the pennies were placed in separate 150mL beakers with 25mL of 6M Nitric acid (HNO3), in order to dissolve the pennies. Following this, each penny solution was quantitatively transferred into separate 100mL volumetric flasks and then each solution had 14mL of concentrated ammonia in order to develop a deep blue color. The solutions were then each diluted and thoroughly mixed. To finalize this step, each of the three solutions were placed in cuvettes. The last step, spectrometer analysis, required that the Vernier Labquest spectrometer be set up and calibrated with the 0.00g/L solution. After this was done the contents of the cuvette were emptied and then rinsed and filled with the most concentrated standard solution. The spectrometer was then set to “play”, the cuvette was inserted, and the approximate wavelength ofmaximum absorbance was then recorded in the notebook. This wavelength was then used as the max and used to determine the absorption rate. This step was repeated with the rest of the standard solutions going from most to least concentrated. The values for concentration and absorption were recorded throughout this step. Following this, the new penny solutions were alsomeasured using the spectrometer. 3
CalculationsThe data analysis was carried out after the experiment was over. While still in the lab, a logger pro calibration curve was created to plot absorbance versus concentration of the five standard solutions. The 0.00g/L was excluded from the data points as it was used to calibrate the instruments. The new graph was then shown to the TA for approval. Outside of the lab, the equation of the line and absorbance values were used to interpolate the concentration of Cu in each penny solution. The grams of copper in each penny where calculated for by multiplying the interpolated value and the amount of solution in the volumetric flask. After this was done, the