Principles of Instrumental Analysis
7th Edition
ISBN: 9781305577213
Author: Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher: Cengage Learning
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Question
Chapter 14, Problem 14.4QAP
Interpretation Introduction
Interpretation:
The sketch of the photometric titration curve for the titration of Iron(III) with
Concept introduction:
The photometric titration curve is the plot showing the relationship between the absorbance of the solution corrected for the particular volume changes versus the volume of the titrant present in the solution.
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A spectrophotometric method for the determination of Fe (II) is based on the measurement of the red-orange color of its complex with o-phenanthroline. The complex obeys Beer's law for Fe (II) concentrations lower than 9 ppm. It is known that a solution containing 0.100 ppm of Fe(II) in excess of o-phenanthroline produces an absorbance of 0.200 in a cuvette with 1.00 cm of optical path and that an unknown sample gives an absorbance of 0.470 under the same conditions,
Calculate:
a) The concentration of Fe in the unknown sample in moles/L and ppm.
b) The molar absorptivity coefficient of the complex.
Fact. Fe = 55.845
1.Solution of EDTA is particularly valuable as titrants because the reagent
combines with metal ions in a 1:1 ratio regardless of the charge on the
cation. For example, Fe(ll) and Fe(ll), complexes are formed with EDTA
with great stability. The formation constants for the Fe(ll)-EDTA chelate,
and Fe(lll)-EDTA chelate are 2.1 x 1014 and 1.3 X 1025, respectively.
a) For each ion complex mentioned above, write the equations of reactions
for complex formation and expression for the complex formation
constant.
b) Calculate the concentration of Fet In a solution that was prepared by
mixing 50.0 mL of 0.200 M Fohwith 200 0 o/oro.0100 M EDTA. The
mixture was buffered to a ph of 11.00,
(Given the valio of a, 0.85 al pH I1.00)
The complex formation reaction is given by:
Ca^2+ + EDTA = CaY^2-
1.Calculate the concentration of free Ca^2+ in a solution of 0.10M CaY^2- at pH 10.00,given that the formation constant for CaY^2- is 10^10.65 and aY4- =0.30 at a pH of 10.00
2.How would the amount of Ca^2+ in the solution change if the pH of the solution was lowered to the pH of 6.(Note:it is not necessary to do the calculation)
Chapter 14 Solutions
Principles of Instrumental Analysis
Ch. 14 - Prob. 14.1QAPCh. 14 - A 0.4740-g pesticide sample was decomposed by wet...Ch. 14 - Sketch a photometric titration curve for the...Ch. 14 - Prob. 14.4QAPCh. 14 - Prob. 14.5QAPCh. 14 - The accompanying data (1.00-cm cells) were...Ch. 14 - A 3.03-g petroleum specimen was decomposed by wet...Ch. 14 - Prob. 14.8QAPCh. 14 - Prob. 14.9QAPCh. 14 - The acid-base indicator HIn undergoes the...
Ch. 14 - Prob. 14.11QAPCh. 14 - Prob. 14.12QAPCh. 14 - Copper(II) forms a 1:1 complex with the organic...Ch. 14 - Aluminum forms a 1:1 complex with...Ch. 14 - Prob. 14.15QAPCh. 14 - Prob. 14.16QAPCh. 14 - Prob. 14.17QAPCh. 14 - Prob. 14.18QAPCh. 14 - Prob. 14.19QAPCh. 14 - Given the Information that...Ch. 14 - Prob. 14.21QAPCh. 14 - Mixing the chelating reagent B with Ni(II) forms...Ch. 14 - Prob. 14.23QAP
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