Lab 4: Spectrophotometric Analysis of Copper Ion Solutions
Record all measured data and calculated data with the correct number of significant
figures and with correct units.
Part 1: Determining Wavelength of Maximum Absorbance
1. Describe the solution concentrations and the wavelengths of maximum absorbance for both the copper(II)
sulfate and the cobalt(II) chloride solutions. Also record the absorbance value at the wavelength of maximum
absorbance for each solution.
Solution Concentration (M) Wavelengthmax (nm) Absorbance
CuSO4 0.060 700 0.517
CoCl2 0.025 520 0.364
2. (a) Compare the color of each solution to the color of the wavelength of light that is absorbed most
effectively – shown by the wavelength of maximum absorbance. For each solution, explain how the colors
relate to one another on the color wheel shown in the background.
CuSO4 (light blue solution) corresponds to the max absorbance of red orange.
CoCl2 (pink-red solution) corresponds to the max absorbance of green.
(b) Explain your answer to 2(a) in terms of “light absorbed” vs. “light reflected” by the solution.
The light absorbed for CuSO4 is red orange which is why we cannot see it with
our eyes and the light blue color of the solution is what is being reflected to our
eyes. Same goes for the light absorbed for CoCl2 which is green, and the light
reflected is the color of the solution: pink/red. Both colors that are being absorbed
are opposite of the reflected colors that are shown on the color wheel.
Part 2: Developing a Standard Curve from Known Concentrations
3. Show your work for calculating the concentration of CuSO4 in the solutions in Flasks 1-4. These are dilution
calculations (reference Section 4.5 in the ebook). Include units on all values used in your calculations and
remember to report calculated values with correct significant figures and units.
Flask 1: M2 = = 0.012 M
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Record all measured data and calculated data with the correct number of significant
figures and with correct units.
Part 1: Determining Wavelength of Maximum Absorbance
1. Describe the solution concentrations and the wavelengths of maximum absorbance for both the copper(II)
sulfate and the cobalt(II) chloride solutions. Also record the absorbance value at the wavelength of maximum
absorbance for each solution.
Solution Concentration (M) Wavelengthmax (nm) Absorbance
CuSO4 0.060 700 0.517
CoCl2 0.025 520 0.364
2. (a) Compare the color of each solution to the color of the wavelength of light that is absorbed most
effectively – shown by the wavelength of maximum absorbance. For each solution, explain how the colors
relate to one another on the color wheel shown in the background.
CuSO4 (light blue solution) corresponds to the max absorbance of red orange.
CoCl2 (pink-red solution) corresponds to the max absorbance of green.
(b) Explain your answer to 2(a) in terms of “light absorbed” vs. “light reflected” by the solution.
The light absorbed for CuSO4 is red orange which is why we cannot see it with
our eyes and the light blue color of the solution is what is being reflected to our
eyes. Same goes for the light absorbed for CoCl2 which is green, and the light
reflected is the color of the solution: pink/red. Both colors that are being absorbed
are opposite of the reflected colors that are shown on the color wheel.
Part 2: Developing a Standard Curve from Known Concentrations
3. Show your work for calculating the concentration of CuSO4 in the solutions in Flasks 1-4. These are dilution
calculations (reference Section 4.5 in the ebook). Include units on all values used in your calculations and
remember to report calculated values with correct significant figures and units.
Flask 1: M2 = = 0.012 M
This study source was downloaded by 100000897367967 from CourseHero.com on 03-30-2025 09:33:46 GMT -05:00
https://www.coursehero.com/file/248121393/Lab-4-Assignmentdocx/
