To spectrophotometrically determine the mass percent of copper in an ore containing copper and some inert materials, solutions with known [Cu?2+] are prepared and the absorbance of each of the...

To spectrophotometrically determine the mass percent of copper in an ore containing copper and some inert materials, solutions with known [Cu?2+] are prepared and the absorbance of each of the solutions is measured at the wavelength of optimum absorbance. The data are used to create a calibration plot, as shown below. A 0.630 g sample of the ore is completely dissolved in concentrated HNO?3(?aq?). The mixture is diluted with water to a final volume of 50.00 mL. Assume that all of the cobalt in the ore sample is converted to Cu?2+(?aq?). (a) What is [Cu?2+] in the solution if the absorbance in a sample of the solution is 0.74? (b) Calculate the number of moles of Cu?2+(?aq)? in the 50.00 mL solution. ?(c) Calculate the mass percent of Cu?2+ in the 0.630 g sample of the ore?