2. To spectrophotometrically determine the mass percent of cobalt in an ore containing cobalt and some inert materials, solutions with known [Co2+] 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, shown below. Absorbance 0.90- 0.80- 0.70- 0.60- 0.50 0.40- 0.30- 0.20- 0.10- 0.00++ 0 0.005 0.0103 0.015 Concentration (M) .04. A 0.630 g sample of the ore is completely dissolved in concentrated HNO3(aq). The mixture is diluted with water to a final volume of 50.00 mL. Assume that all the cobalt in the ore sample is converted to Co²+ (aq). (a) What is the [Co2+] in the solution if the absorbance of a sample of the solution is 0.74 ? (b) Calculate the number of moles of Co²+ (aq) in the 50.00 mL solution. (c) Calculate the mass percent of Co in the 0.630 g sample of the ore.

2. To spectrophotometrically determine the mass percent of cobalt in an ore containing cobalt and some inert materials, solutions with known [Co2+] 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, shown below. Absorbance 0.90- 0.80- 0.70- 0.60- 0.50 0.40- 0.30- 0.20- 0.10- 0.00++ 0 0.005 0.0103 0.015 Concentration (M) .04. A 0.630 g sample of the ore is completely dissolved in concentrated HNO3(aq). The mixture is diluted with water to a final volume of 50.00 mL. Assume that all the cobalt in the ore sample is converted to Co²+ (aq). (a) What is the [Co2+] in the solution if the absorbance of a sample of the solution is 0.74 ? (b) Calculate the number of moles of Co²+ (aq) in the 50.00 mL solution. (c) Calculate the mass percent of Co in the 0.630 g sample of the ore.

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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