Percent Cu2 + In A Mineral Sample

Purpose/ Methods The purpose of this experiment was to determine the mass percent Cu2+ in a mineral sample (Malachite), and a rock sample (copper ore). Through the process of spectroscopy, the students were able to determine the percent of copper that each sample yielded. The students were also able to apply the information to the theoretical value of copper in malachite to determine the percent error of the mineral mass percent. Furthermore, the methods used in the experiment provide insight into how mining companies determine whether a copper ore mining site will be profitable or not. Mining companies must evaluate samples of rock to determine the percent copper which would provide the most and the purest copper for production of everyday

The mineral sample was rinsed with distilled water and filtered into a volumetric flask (50 mL). (Some errors occurred at this portion of the experiment, because the funnel was too close to the flask. No solution could filter through until it was lifted. When lifted, some solution spilled.) Next 15M NH4OH “ammonium hydroxide” (4mL) was added to the volumetric flask. Then the flask was filled the rest of the way with distilled water to the mark. Similar steps were taken for the rock solution. The rock solution from the prior lab was filtered into a volumetric flask (100mL), then 15 M NH4¬OH (8mL) was added to the flask. After that, the flask was filled to the mark with distilled water. Both flasks were then swirled to combine the solution
Copper Standard Solutions Preparation: To prepare the copper standard solutions the students added 15 M NH¬4OH (4mL) to a designated amount of stock solution (0.100 M) in a volumetric flask (50mL). Standards one through six contained the following mL of original stock solution: 1.00, 2.00, 4.00, 6.00, 8.00, and 10.00. Once each of these solutions were combined with the ammonium hydroxide (4 mL) they were filled to the mark on the volumetric flask (50mL) with distilled water and swirled.
Recording Absorption

Further experimentation with multiple trials could strengthen these results. Although some errors were made with the mineral solution from the filtration process, the percent error calculated for the mineral was partially accurate. The theoretical value of Cu2+was calculated to be 57.48%, while the experimental value was 50.6%. The percent error was was not below 5 percent, but it was below 20 percent, which is fairly good. This result supports that the methods used during this experiment are sound. As for the rock portion of the experiment, the students concluded that the mass percent of copper was 3.1%. This mass percent of Cu2+ is above the accepted value of 1.0 percent copper, which is the economically viable percent for mining copper ore. From this value of 1% copper in copper ore manufacturers can extract 9.99% pure copper (Copper Mining and Processing: What is Copper?, n.d.). These results show that the provided sample of copper ore would be worth mining, since it contains a higher percent of cu2+ than is needed to mine for copper. Overall, the experiment was accurate in determining the mass percent of cu2+ in the rock sample. Further experimentation could be done, to reduce the risk of errors within the measuring of the absorbance of standards which may have occurs. If the error of not wiping the cuvette