are &c. = = 5-18. Molar absorptivity data for the cobalt and nickel complexes with 2,3-quinoxalinedithiol 36,400 and &Ni = 5520 at 510 nm and &c. = 1240 and EN 17,500 at 656 nm. A 0.425-g sample was dissolved and diluted to 50.0 mL. A 25.0-mL aliquot was treated to eliminate interferences; after addition of 2,3-quinoxalinedithiol, the volume was adjusted to 50.0 mL. This solution had an absorbance of 0.446 at 510 nm and 0.326 at 656 nm in a 1.00-cm cell. Cal- culate the concentration in parts per million of cobalt and nickel in the sample. 26

are &c. = = 5-18. Molar absorptivity data for the cobalt and nickel complexes with 2,3-quinoxalinedithiol 36,400 and &Ni = 5520 at 510 nm and &c. = 1240 and EN 17,500 at 656 nm. A 0.425-g sample was dissolved and diluted to 50.0 mL. A 25.0-mL aliquot was treated to eliminate interferences; after addition of 2,3-quinoxalinedithiol, the volume was adjusted to 50.0 mL. This solution had an absorbance of 0.446 at 510 nm and 0.326 at 656 nm in a 1.00-cm cell. Cal- culate the concentration in parts per million of cobalt and nickel in the sample. 26

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter8: Sampling, Standardization, And Calibration

Section: Chapter Questions

Problem 8.23QAP

See similar textbooks

Similar questions

From the data in Problem 26-14, calculate for species C and D) (a) the resolution. (b) the length of column necessary to separate the two species with a resolution of 2.5.
The accompanying data (1.00-cm cells) were obtained for the spectrophotometric titration 10.00 mL of Pd(II) with 2.44 10-4 M Nitroso R(O. W Rollins and M. M. Oldham, Anal. chem .,1971, 43, 262, DOI: 10.1021/ac60297a026). Calculate the concentration of the Pd(II) solution, given that the ligand-to-cation ratio in the colored product is 2:1
The molar absorptivities of compounds X and Y were measured with pure samples of each: ε (M-1 cm-1) λ (nm) X Y 272 16,440 3,870 327 3,990 6,420 A mixture of compounds X and Y in a 1.00-cm cell had an absorbance of 0.957 at 272 nm and 0.559 at 327 nm. Find the concentrations of Y in the mixture. 4.43 x 10-5 M 3.03 x 10-6 M 5.95 x 10-5 M 3.56 x 10-4 M
A solution of Tryptophan has an absorbance at 280 nm of 0.54 in a 0.5 cm length cuvette. Given the absorbance coefficient of trp is 6.4 x 103 Lmol-1cm-1. What is the concentration of solution?
21. (What exactly is meant by potentiometric methods? What are they even?)
Calculate the Mg (OH) 2 content of MOM, 13.2 g of which was dissolved in 55.00 mL of 1.2642 NH2S04 producing a mixture that required 25.3 mL of 1.771 N NaH. Mg(OH)2 has MW=58.32 andfeq=2
The molar absorptivity for cobalt and nickel complexes with 2,3-quinoxalinedithiol are 3.64x104L/M-cm for Co at 510nm, 5.52x103L/M-cm and 1.24x103L/M-cm for Co at 656nm and 1.75x104L/M-cm for Ni. A 250mg soil sample that was collected near an industrial metal-processing plant is dissolved, and masking agent is added to avoid interference from other metals present. Color is developed by adding the complexing agent and the sample is diluted to 100.00ml. The absorbance at 510nm is 0.517 and at 656nm it is 0.405 in a 1.00cm cell. Calculate the weight percent of Co and Ni in the soil.
You obtained the following raw data when setting up a Biuret standard curve: BSA (mg/ml) Absorbancy 540nm 0 0.158 1 0.210 2 0.260 3 0.305 4 0.360 5 0.410 6 0.455 7 0.510 8 0.530 9 0.550 10 0.554 After blanking against a biuret-dH2O sample, the protein concentration of an unknown sample was determined using the same method and an absorbancy of 0.251 was obtained. Set up a standard curve, excluding outliers (experimental and statistical) and determine the protein concentration in the unknown sample in mg / ml (up to 3 significant figures).
Why is glass better than fused silica as a prism construction material for a monochromator to be used in the region of 400 to 80 nm?
The same polar compound is gas chromatographed on an SE-30 (very nonpolar) column and then on a Carbowax 20M (very polar column). I low will K=cS/cM vary between the two columns?
The acid-base indicator HIn undergoes the following reaction in dilute aqueous solution: HIncolor1H++Incolor2 The following absorbance data were obtained for a 5.00 I0-4 M solution of HIn in 0.1 M NaOH and 0.1 M HC1. Measurements were made at wavelengths of 485 nm and 625 nm with 1.00-cm cells. 0.1 M NaOH A485 = 0.075 A625 = 0.904 0.1 M HC1 A485 = 0.487 A625 = 0.181 In the NaOH solution, essentially all of the indicator is present as In-; in the acidic solution, it is essentially all in the form of HIn. (a) Calculate molar absorptivities for In- and HIn at 485 and 625 nm. (b) Calculate the acid dissociation constant for the indicator ¡fa pH 5.00 buffer containing a small amount of the indicator exhibits an absorbance of 0.567 at 485 nm and 0.395 at 625 nm (1.00-cm cells). (c) What is the pH of a solution containing a small amount of the indicator that exhibits an absorbance of0.492 at 485 nm and 0.245 at 635 nm (1.00-cm cells)? (d) A 25.00-mL aliquot of a solution of purified weak organic acid HX required exactly 24.20 mL of a standard solution of a strong base to reach a phenolphthalein end point. When exactly 12.10 mL of the base was added to a second 25.00-mL aliquot of the acid, which contained a small amount of the Indicator under consideration, the absorbance was found to be 0.333 at 485 nm and 0.655 at 625 nm (1.00-cmcells). Calculate the pH of the solution and Ka for the weak acid. (e) What would be the absorbance of a solution at 485 and 625 nm (1.50-cm cells) that was 2.00 10-4 M in the indicator and was buffered to a pH of 6.000?