The 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+ solution with an unknown concentration and an absorbance value of 0.392. The slope-intercept form of the equation of the line is y= 4538.1x +0.0077. The unknown was analyzed on the same instrument as the standard curve solutions at the same temperature. What is the Fe3+ concentration of the unknown solution? [Fe³+] = mol/L Absorbance Iron(III) thiocynate standard curve 1.0 0.5- 0 0.0001 Fe³+ concentration (M) 0.0002

The 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+ solution with an unknown concentration and an absorbance value of 0.392. The slope-intercept form of the equation of the line is y= 4538.1x +0.0077. The unknown was analyzed on the same instrument as the standard curve solutions at the same temperature. What is the Fe3+ concentration of the unknown solution? [Fe³+] = mol/L Absorbance Iron(III) thiocynate standard curve 1.0 0.5- 0 0.0001 Fe³+ concentration (M) 0.0002

Chemistry: Principles and Reactions

8th Edition

ISBN:9781305079373

Author:William L. Masterton, Cecile N. Hurley

Publisher:William L. Masterton, Cecile N. Hurley

Chapter19: Complex Ions

Section: Chapter Questions

Problem 45QAP

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The 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=4558.4⁢x+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?
A standard solution was put through appropriate dilutions to give the concentrations of iron shown in the table that follows. The iron(II)-1,10-phenanthroline complex was then formed in 25.0-mL aliquots of these solutions, following which each was diluted to 50.0 mL. The following absorbances (1.00-cm cells) were recorded at 510 nm: Calculate the concentration, in ppm, of a sample with an abosrbance of 0.829. Fe(II) concentration (ppm) A510 4.00 0.160 10.0 0.390 16.0 0.630 24.0 0.950 32.0 1.260 40.0 1.580
The 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+?
5- A 5.0 mL solution containing 3.36 pm Fe(Ill) ions is diluted to 50.0 mL by first treating with an excess of an appropriate amount of KSCN solution. The molar absorptivity of the FeSCN^2+ complex formed at 580 nm is given 7.0x10^3 L/cm.mol. Which of the following values is the absorbance of this solution as measured with a 2.0 cm cell? Fe:56 A. 0.168 B. 0042 C. 0,084 D. 0.126
Solutions of cobalt (II) ions have a magenta color with a molar absorptivity constant (e) value at 511 nm of 5.87 M-1cm-1. A 0.500 mL sample is transferred from a 50.0 mL stock solution of Co(NO3)2 and diluted with water to a final volume of 7.50 mL. The dilution had an absorbance value at 511 nm in a standard cuvette (1.00 cm light path) of 0.382. Calculate the mass of Co(NO3)2 contained in the original 50.0 mL stock solution.
A mixture is prepared by combining 11.34 mL of 2.36 x 103 M Fe(NO3)3 with 10.00 mL of 1.66 x 10-3 M KSCN. The solution turns red due to the formation of FeSCN2+. The absorbance is measured and, using a calibration plot, the [FESCN2*] at equilibrium is found to be 2.20 x 10-4 M. Complete the following ICE table Fe3+ SCN 1t FESCN2+ initial (M) (A) (B) (C)0 change (M) (D) (E) (F) equilibrium (M) (G) (H) (1) What is the value of K?
A 2.78 ✕ 10−4 M solution of a compound has an absorbance of 0.417 at 520 nm in a 1.00 cm cell. The solvent's absorbance under the same conditions is 0.020. (a) What is the molar absorptivity of the unknown compound? M -1cm-1(b) What is the concentration of the compound in a solution, if the absorbance of the solution in a 1.00 cm cell at 520 nm is 0.391? M
A 2.50 mL aliquot of a solution that contains 3.85 ppm Fe(III) is treated with an appropriate excess of KSCN and diluted to 100.0 mL. What is the absorbance of the resulting solution at 580 nm in a 0.50 cm cell? (Molar absorptivity of Fe (SCN)2+is 7.0 x 105L mol-1cm-1).
A student measures k for a certain blue dye to be 400.4 M-1 at 560 nm. What is the molarity of the dye in a solution with an absorbance of 0.118 at this wavelength?
4. The %Mn in steel can also be determined spectrophotometrically by oxidizing the manganese to the intensely colored permanganate, MnO4-. Standard solutions of permanganate gave the following absorbances (in a 1 cm cell): ABSORBANCE CONC. OF MnO4 (g/mL) 0.210 1.05 x 10-5 0.315 1.61 x 10-5 0.429 2.21 x 10-5 0.599 2.98 x 10-5 0.801 4.04 x 10-5 The following samples of steel were thoroughly reacted to convert the manganese into permanganate and then diluted to 500.00 mL. WT. OF STEEL (g) ABSORBANCE 0.5886 0.611 0.3498 0.359 0.4555 0.482 Again using Excel, plot the calibration data and calculate the %Mn in the steel.
At 590 nm, crystal violet (a biological stain) has a molar absorptivity (ε) of 8.7×104 M-1cm-1. Using Beer's Law, calculate the concentration of crystal violet in a solution with a measured absorbance (A) of 1.254. The path length (b) is 1.00 cm.
The sodiuṁ salt of 2-quinizarinsulfonic acid (NaQ) forms a complex with Al3+ that absorbs strongly at 560 nm. From the data of the absorbance, find formula of the complex. In all solutions, [A3+]=3.7x105 M and the cell length is 1.00 cm. (Apply the molar-ratio method.) ca/M A(560) mol ratio [Al3+]/[Q] 1,00E-05 0,131 2,00E-05 0,265 3,00E-05 0,396 4,00E-05 0,468 5,00E-05 0,487 6,00E-05 0,498 8,00E-05 0,499 1,00E-04 0,5 OH NaQ