Concept explainers
(a)
Interpretation:
A calibration curve from the given data should be plotted.
Concept introduction:
A calibration curve or standard curve is a method used in
(b)
Interpretation:
Using the method of least squares, an equation relating absorbance and the concentration of Fe(II) should be developed.
Concept introduction:
For equations,
The slope of the line,
The intercept,
(c)
Interpretation:
The standard deviation of the slope and the intercept should be calculated.
Concept introduction:
Standard deviation about regression,
N − number of points used.
The standard deviation of the slope,
The standard deviation of the intercept,
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Chapter 14 Solutions
Principles of Instrumental Analysis, 6th Edition
- A solution containing the complex formed between Bi(III) and thiourea has a molar absorptivity of 9.32 x 103 M-1 cm-1 at 470 nm. (a) Calculate the absorption of a 4.25x10-5 M solution of the complex at 470 nm in a 1-cm cell. (b) What is the molar concentration of the complex in a solution that has the calculated absorption in (a) when measured at 470 nm in a 2.50 cm cell?arrow_forwardThe molar absorptivity (ε) of the FeSCN2+ complex ion is 4700 M-1 · cm-1 at a wavelength of 450 nm. Using a 1-cm sample tube, you measure the absorbance as (2.0x10-1). What is the concentration of FeSCN2+?arrow_forwardA solution in part C initially contains (4.1000x10^-4) molar SCN¯ and (1.180x10^-1) molar Fe3+. This solution was then measured using the colorimeter, and an absorbance of (5.150x10^-1) was recorded.The constant determined in part A of the experiment was found to be (3.47x10^3). Using the absorbance and constant provided, determine the equilibrium concentration of FESCN2+, [FESCN2*]E. Note: Your answer is assumed to be reduced to the highest power possible. Your Answer: х10 Answer unitsarrow_forward
- A series of standard iron-phenanthroline [Fe(phen)3]2+ complex ion solutions were prepared. The absorbance of each solution was measured at a wavelength of 510 mm. A calibration curve of absorbance vs. concentration was then plotted to obtain a linear equation of y = 0.0018x+0.0749. The absorbance of an unknown [Felphenly solution was measured to be 0.326. Calculate the concentration of the complex ion. NOTE! Report your answer as a WHOLE #. Type your answer...arrow_forwardThe standard curve was made by spectrophotographic analysis of equilibrated iron(III) thiocyanate solutions of known concentration. You are asked to analyze a Fe(SCN)2+Fe(SCN)2+ solution with an unknown concentration and an absorbance value of 0.4150.415 . The slope-intercept form of the equation of the line is ?=4558.4?+0.0147y=4558.4x+0.0147 . The unknown was analyzed on the same instrument as the standard curve solutions at the same temperature. What is the Fe3+Fe3+ concentration of the unknown solution?arrow_forwardA solution in part C initially contains (4.06x10^-4) molar SCN¯ and (2.960x10^-3) molar Fe3+. This solution was then measured using the colorimeter, and an absorbance of (4.9800x10^-1) was recorded.The constant determined in part A of the experiment was found to be (3.8200x10^3). Using the data provided above, determine the equilibrium concentration of SCN", [SCN]E in this solution. Note: Your answer is assumed to be reduced to the highest power possible. Your Answer: x10 Answer unitsarrow_forward
- A solution in part C initially contains (4.2100x10^-4) molar SCN¯ and (3.1700x10^-3) molar Fe3+ This solution was then measured using the colorimeter, and an absorbance of (5.01x10^-1) was recorded.The constant determined in part A of the experiment was found to be (3.4800x10^3). Using the data provided above, determine the equilibrium concentration of Fe3+ [Fe3+ ]e in this solution. Note: Your answer is assumed to be reduced to the highest power possible. Your Answer: x10 Answer unitsarrow_forwardAt 580 nm, the wavelength of its maximum absorption, the complex Fe(SCN)2+ has a molar absorptivity of 7.00 X 103 L mol-1 cm-1. Calculate (a) the absorbance of a 2.50 X 10-5 M solution of the complex at 580 nm in a 1.00-cm cell. (b) the absorbance of the solution in which the concentration of the complex is twice that in part (a) (c) the transmittance of the solutions described in parts (a) and (b) (d) the absorbance of a solution that has half the transmittance of that described in part (a) answer letter d pleasearrow_forwardAt 580 nm, the wavelength of its maximum absorption, the complex Fe(SCN)2+ has a molar absorptivity of 7.00 X 103 L mol-1 cm-1. Calculate (a) the absorbance of a 2.50 X 10-5 M solution of the complex at 580 nm in a 1.00-cm cell. (b) the absorbance of the solution in which the concentration of the complex is twice that in part (a) (c) the transmittance of the solutions described in parts (a) and (b) (d) the absorbance of a solution that has half the transmittance of that described in part (a)arrow_forward
- The complex formed between Cu(I) and 1,10- phenanthroline has a molar absorptivity of 7000 L cm-1 mol-1 at 435 nm, the wavelength of maximum absorption. What is the the absorbance of a 6.17 x 10-5 M solution of the complex when measured in a 1.00-cm cell at 435 nm.arrow_forwardA solution in part B initially contains (4.0800x10^-4) molar SCN and (2.850x10^-3) molar Fe3+ This solution was then measured using the colorimeter, and an absorbance of (4.810x10^-1) was recorded.The calibration curve prepared in part A of the experiment yielded a linear fit equation of y = (3.72o0x10^3)x+(4.16x10^-2) and an R2 value of 0.9964. Using the data provided above, determine the equilibrium concentration of Fe3+, [Fe* le in this solution. Note: Your answer is assumed to be reduced to the highest power possible. Your Answer: x10 Answer unitsarrow_forwardYou wish to measure the iron content of the well water on the new property you are about to buy. You prepare a reference standard Fe3+ solution with a concentration of 5.53×10−4 M. You treat 10.0 mL of this reference with HNO3 and excess KSCN to form a red complex and dilute the reference to 45.0 mL. The diluted reference is placed in a cell with a 1.00‑cm light path. You then take 20.0 mL of the well water, treat with HNO3 and excess KSCN, and dilute to 100.0 mL. This diluted sample is placed in a variable pathlength cell. The absorbance of the reference and the sample solutions match when the pathlength is 3.25cm. What is the concentration of iron in the well water? For each solution, the zero is set with a blank.arrow_forward
- Principles of Instrumental AnalysisChemistryISBN:9781305577213Author:Douglas A. Skoog, F. James Holler, Stanley R. CrouchPublisher:Cengage Learning