Plot the calibration curve of absorbance versus molar concentration for the standard solutions. nly do Calculate the absorptivity coefficient for the metal ion.
Plot the calibration curve of absorbance versus molar concentration for the standard solutions. nly do Calculate the absorptivity coefficient for the metal ion.
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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Help! I am trying to figure out part c of this report sheet and I am not sure of the absorbance or how to plot the calibration curve
![anly do not reproduce.
curve of
of absorbance versus molar concentration for the standard solutions. Data Analysis, F, G
Calculate the absorptivity coefficient for the metal ion.
drobinson@a
Have the instructor approve your graph.
Plot the calibration curve
D. Unknown Metal Ion Concentration
Personal use only, de
2020-09-17
1. Prepare the unknown. Describe the preparation for the solution containing the unknown concentration of the
metal ion.
Volume of unknown sample solution (mL) drobinson@alamo.edu.
Volume of diluted sample (mL)
2. Concentration of metal ion. Absorbance of metal ion in solution
Concentration of metal ion from the calibration curve (mol/L)
Concentration of metal ion in the original sample corrected for dilution (mol/L) use only, do not reproduce.
PET
Show your calculations to account for the dilution of the original sample.
reproduce
Concentration of metal ion in the original sample (mass/volume).
Ons
Show calculations.
3. Expressing Concentration. Express the concentration of the metal ion in the sample in appropriate units of mass/
volume [i.e., pph (percent), ppm, ppb, etc.].
2020-09
drobinson@alamo.edu
70947
drobinson@alamo.edu
Laboratory Questions
Circle the questions that have been assigned.
useproduce
1. Part A.1. For the preparation of the stock solution, 0.01 M HNO3 is used as a diluent rather than deionized water.
Explain why. Hint: Review the solubility rules of transition metal ions in Appendix E.
per
3. Part B.1. Calibration of the spectrophotometer to set the Amax is important for a spectrophotometric analysis. Referring
to Figure 35.1, suppose the wavelength for all subsequent absorbance measurements had been set at 450 nm instead of
the Amax Explain how this would affect the recorded absorbance values for subsequent test solutions. Note: It is not
because the absorbance values would be wrong!
not reprodu
104
2. Part A.2. In diluting the standard solutions, 0.01 M HNO3 is used. In the dilution, is it more important to use the
correct volume or the correct concentration of the HNO, solution for the dilution? Explain.
pena.edu
5. Part D.1. An electrolytic-bath sample containing the metal ion of unknown concentration contains suspended matter.
Because of a lack of time, the absorbance of the sample was measured and recorded as is. As a result, will the concen-
tration of the metal ion in the unknown be reported as too high, too low, or remain unchanged as a result of chemist's
hasty decision? Explain.
4. Part B.2. Will Fe³+ (aq) or Cu²+ (aq) have the shorter Amax for absorption in the visible spectrum? Explain. Hint:
Fe³+ (aq) has an orange-brown color, and Cu²+ (aq) has a blue color. See Dry Lab 3.
Personal
2020-00
6. Part D.2. The cuvet used for the absorbance measurements is not wiped clean with a Kimwipe before the absorbance
measurement. As a result, will the concentration of the metal ion in the unknown be reported as too high, too low, a
remain unchanged as a result of this poor technique? Explain.
Dalamo edu
396 Spectrophotometric Metal Ion Analysis](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F548484be-99c3-4aeb-88da-6f8ddd41520b%2F9920cf2d-98a7-4dad-94f4-5e82ac12f409%2F3gbs0lg_processed.jpeg&w=3840&q=75)
Transcribed Image Text:anly do not reproduce.
curve of
of absorbance versus molar concentration for the standard solutions. Data Analysis, F, G
Calculate the absorptivity coefficient for the metal ion.
drobinson@a
Have the instructor approve your graph.
Plot the calibration curve
D. Unknown Metal Ion Concentration
Personal use only, de
2020-09-17
1. Prepare the unknown. Describe the preparation for the solution containing the unknown concentration of the
metal ion.
Volume of unknown sample solution (mL) drobinson@alamo.edu.
Volume of diluted sample (mL)
2. Concentration of metal ion. Absorbance of metal ion in solution
Concentration of metal ion from the calibration curve (mol/L)
Concentration of metal ion in the original sample corrected for dilution (mol/L) use only, do not reproduce.
PET
Show your calculations to account for the dilution of the original sample.
reproduce
Concentration of metal ion in the original sample (mass/volume).
Ons
Show calculations.
3. Expressing Concentration. Express the concentration of the metal ion in the sample in appropriate units of mass/
volume [i.e., pph (percent), ppm, ppb, etc.].
2020-09
drobinson@alamo.edu
70947
drobinson@alamo.edu
Laboratory Questions
Circle the questions that have been assigned.
useproduce
1. Part A.1. For the preparation of the stock solution, 0.01 M HNO3 is used as a diluent rather than deionized water.
Explain why. Hint: Review the solubility rules of transition metal ions in Appendix E.
per
3. Part B.1. Calibration of the spectrophotometer to set the Amax is important for a spectrophotometric analysis. Referring
to Figure 35.1, suppose the wavelength for all subsequent absorbance measurements had been set at 450 nm instead of
the Amax Explain how this would affect the recorded absorbance values for subsequent test solutions. Note: It is not
because the absorbance values would be wrong!
not reprodu
104
2. Part A.2. In diluting the standard solutions, 0.01 M HNO3 is used. In the dilution, is it more important to use the
correct volume or the correct concentration of the HNO, solution for the dilution? Explain.
pena.edu
5. Part D.1. An electrolytic-bath sample containing the metal ion of unknown concentration contains suspended matter.
Because of a lack of time, the absorbance of the sample was measured and recorded as is. As a result, will the concen-
tration of the metal ion in the unknown be reported as too high, too low, or remain unchanged as a result of chemist's
hasty decision? Explain.
4. Part B.2. Will Fe³+ (aq) or Cu²+ (aq) have the shorter Amax for absorption in the visible spectrum? Explain. Hint:
Fe³+ (aq) has an orange-brown color, and Cu²+ (aq) has a blue color. See Dry Lab 3.
Personal
2020-00
6. Part D.2. The cuvet used for the absorbance measurements is not wiped clean with a Kimwipe before the absorbance
measurement. As a result, will the concentration of the metal ion in the unknown be reported as too high, too low, a
remain unchanged as a result of this poor technique? Explain.
Dalamo edu
396 Spectrophotometric Metal Ion Analysis
Transcribed Image Text:V
A= log
Pars
משו
{T}
%
Date
Lab Sec..
Metal Ion for Analysis Fe NCS
Measured tared mass of metal ion salt (g)
Describe the preparation of the 0.10 M stock solution.
A. A Set of Standard Solutions
@alamo edn
Fe SCN 2+14g/mol
1. Prepare a stock solution. Show the calculation for the mass of metal ion salt in the preparation of the stock solution.
See Prelaboratory Assignment, question 2a.
Standard Solution
Experiment 35 Report Sheet
Spectrophotometric Metal Ion Analysis
Concentration of stock solution (mol/L)_00lm
B. Determination of A max
2. Wavelength scan. Use the following table to record wavelength and absorbance data.
Persor
Abs
A
Abs
Abs
Abs
Blank
1
Name
at
2
3
4
5
others as needed
Alamedu
A
do no
18
RE
amo edu
Plot the data of absorbance versus wavelength to set Amax From the data plot, Amax
Have the instructor approve your graph.
dru0=100%
do not
Volume of Standard
Solution (mL)
not reprod
0
1
5
10
15
20
Oplamo C
A
Peracause on
3=37.8%
1-97.4%
4 = 1,8%
2 = 70.4 %10 5=8,0%
C. Plot the Calibration Curve
1. Absorbance of standard solutions. Read and record the absorbance values for the standard solutions.
2
Y
2020
drobicon@ala.io.edu
Absorbance
2
2.011
2.151
2.423
A
2.750
3.100
Abs
do not reproduce
Desk No.
A
=
Abs
A
450
Calculated Molar
Concentration
Abs
nm
oduce.
(0.01)(0.001) / (0.025) = 0,004
0.01) 0.005)/0.025 = 0.002
(0.01)/ 0.060) / 0.025 = 0.004
(0.01) (0.015) 10.025 = 0.006.
(0.0) (0.020)/0.025 = 0.008
Experiment 35 395
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