Q4/ Six 25 ml volumetric flasks containing 2, 4,6, 8 and 10 ml of a standard solution containing 20 ppm of NiCl2. The absorbance reading were found to be 0.3, 0.45, 0.6, 0.77 and 0.93 by using atomic absorption spectroscopy. Calculate the molar concentration of Ni in the test sample with absorbance 0.56. The atomic weight of Ni 58.7 and CI = 35.5 WISH YOU BEST OF LUCK

Q4/ Six 25 ml volumetric flasks containing 2, 4,6, 8 and 10 ml of a standard solution containing 20 ppm of NiCl2. The absorbance reading were found to be 0.3, 0.45, 0.6, 0.77 and 0.93 by using atomic absorption spectroscopy. Calculate the molar concentration of Ni in the test sample with absorbance 0.56. The atomic weight of Ni 58.7 and CI = 35.5 WISH YOU BEST OF LUCK

Principles of Instrumental Analysis

7th Edition

ISBN:9781305577213

Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Chapter9: Atomic Absorption And Atomic Fluorescence Spectrometry

Section: Chapter Questions

Problem 9.6QAP

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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?
Given the Information that Fe3++Y4FeYKi=1.01025Cu2++Y4CuY2Ki=6.31018 and the further information that, among the several reactants and products, only CuY2- absorbs radiationat 750 nm, describe how Cu(II) could be used as an indicator for the photometric titration of Fe(III) with H2Y2-. Reaction:+ Fe3++ H2Y2- FeY- + 2H+.
Q4/ Six 25 ml volumetric flasks containing 2, 4,6, 8 and 10 ml of a standard solution containing 20 ppm of NiCl2. The absorbance reading were found to be 0.3, 0.45, 0.6, 0.77 and 0.93 by using atomic absorption spectroscopy. Calculate the molar concentration of Ni in the test sample with absorbance 0.56. The atomic weight of Ni 58.7 and CI = 35.5 WISH YOU BEST OF LUCK
3. The lead in a swab sample, lead standards, together with a blank were made up in 5.00 mL volumetric flasks using 0.2 % HNO3. 20 μL aliquots of these solutions were injected into the spectrophotometer and the absorbance measured at 217 nm. The following results were obtained. lead / ppb Absorbance 0 0.0591 10.00 0.0858 50.00 0.1926 100.0 0.3260 150.0 0.4594 200.0 0.5929 Swab sample 0.3700 (a) Determine the amount of lead in the swab sample in μg.
Preparing a standard curve. 1. determine the absorbance max of [FeSCN]2+ it is 448.1 2. determine the concentration of FeSCN2+ in the stock solution. M1V1=M2V2 stock solution: ~0.200 M iron (iii) nitrate in 1M nitric acid intial volume: 0.3mL final volume: 10.3mL volume: 10mL ~0.002M potassium thiocyanate initial volume: 0.3mL final volume: 10.3mL volume: 10mL not sure if this is needed stock solutions: ~0.200M iron (iii) nitrate in 1M nitric acid: 0.207M ~0.002M iron (iii) nitrate in 1M nitric acid: 0.00209M ~0.002M potassium thiocyanate: 0.00193M
An unknown concentration of [FeSal]+ gave an absorbance reading of 0.301. Calculate the concentration of the solution, given that the slope of the standard curve was 1280 and the y intercept was -0.00821.
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.
An unknown sample of Yellow 6 solution has the absorbance equal to 0.96. The slope of the Beer's law calibration plot constructed using a 3.8E-5M stock solution of Yellow 6 is 0.0117 (%) 1. What is the molar concentration of the unknown sample (in mole L-¹)? Please give your answer to 3 significant figures (1 additional SF is used to minimize rounding errors). M Hint
Quinine in a 1.664 g antimalarial tablet was dissolved in sufficient 0.10 M HCl to give 500 mL of solution. A 15.00 mL aliquot was then diluted to 100.0 mL with the acid. The fluorescense intensity for the diluted sample at 347.5 nm provided a reading of 288 on an arbitrary scale. A standard 100 ppm quinine solution registered 180 when measured under conditions identical to those for the diluted sample. Calculate the mass in milligrams of quinine in the tablet.
The absorbances of solutions containing K2CrO4 in 0.05 M KOH were measured in a 1.0-cm cell of 375 nm. The following results were obtained: Calculate the linear equation of the calibration curve.
6. In a flame spectrometric determination of sodium, lithium is used as an internal standard. Assume the spectrum of a standard solution that contains 2.00 ppm Na and 100 ppm Li shows two peaks with intensities of Ina= 4.22 and I= 9.24, respectively. An unknown sample solution that also contains 100 ppm Li gives two peaks with intensities of Ina = 6.16 and I= 8.24, respectively. Calculate the concentration of Na in the unknown sample in ppm. А. 3.08 рpm В. 6.16 рpm С. 4.22 рpm D. 3.27 ppm Е. 12.1 ppm
Suppose that you are trying to measure the concentration of SO2 in air. To do that, you followed the para-rosaniline method. The SO2 was collected in a 10-ml solution of HgCl4 2- then diluted to 25 ml after the addition of the appropriate reagents. The absorbance owas measured at 650 nm in a 2.0-cm cell, yielding a value of 0.535. A standard sample was prepared by substituting a 1.00 mL sample of a standard solution containing the equivalent of 15.00 ppm SO2 for the airsample. The absorbance of the standard is found out to be 0.191. Report the concentration of SO2 in the air in parts per million. The density of air is 1.19 g/L