A spectrophotometer was calibrated with a 7.236 x 10-4 M (in Cu) Cu-neocuproine solution. This calibration was carried out in a 1.00 cm cell, and yielded an absorbance of 0.2680 AU. An unknown was then analyzed in this same spectrophotometer, but using a 2.50 cm cell. If the absorbance of the unknown was 0.3700 AU, what is the Cu concentration? M Submit Answer

A spectrophotometer was calibrated with a 7.236 x 10-4 M (in Cu) Cu-neocuproine solution. This calibration was carried out in a 1.00 cm cell, and yielded an absorbance of 0.2680 AU. An unknown was then analyzed in this same spectrophotometer, but using a 2.50 cm cell. If the absorbance of the unknown was 0.3700 AU, what is the Cu concentration? M Submit Answer

Appl Of Ms Excel In Analytical Chemistry

2nd Edition

ISBN:9781285686691

Author:Crouch

Publisher:Crouch

Chapter12: Spectrochemical Methods

Section: Chapter Questions

Problem 10P

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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.
A 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 units
The determination of iron in wines was carried out by atomic absorption spectrophotometry, using the standard addition method. To do this, 10 mL of wine were placed in five 50 mL volumetric flasks; then 0, 5, 10, 15 and 20 mL of a 10 ppm iron standard solution were added to each of them. Next, they were gauged with distilled water and the absorbance was measured, obtaining the values of 0.040, 0.062, 0.081, 0.102 and 0.125 respectively. Calculate the regression parameters and obtain the iron concentration in the wine, in µg / mL.
"[FeSCN2+]eq is calculated using the formula: [FeSCN2+]eq = Aeq/Astd x [FeSCN2+]std where Aeq and Astd are the absorbance values for the equilibrium and standard sample respectively." I am confused about what Aeq and Astd mean. We did an experiment where we measured the absorption of this chemical formation and I got around 0.18. Is that one of the values?
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
A chemist received a report from an analysis involving the iron-phenanthroline method, containing the calibration curve for Fe standards (20 ppm, 30 ppm, 40 ppm, 50 ppm, and 60 ppm) and their corrected absorbances. The report stated that the equation of the line and r² were as follows: y = 0.015066 x -0.154424 r² = 0.9997 The sample they tested gave a corrected reading of 0.417. How much Fe is present in ppm? (A) 2.80 B) 37.93 17.43 D) 2.60
A 10 cm 3 air saturated Fricke dosimetry solution in a 1 cm diameter tube is irradiated for 10 min in a 6~ source of gamma rays. The optical density measured at 304 txm in a 1 cm light path at 30~ was 0.260 after the completion of irradiation and 0.003 before irradiation. (a) What is the total dose in gray absorbed by the solution?(b) If 10 cm 3 of methanol is irradiated in the same tube for the same 10min, what is the absorbed dose in gray. The Z/A for methanol is 0.562 and that for the Fricke dosimeter is 0.553. Explain any assumption you make to solve the problem.
A chemist received a report from an analysis involving the iron-phenanthroline method, containing the calibration curve for Fe standards (20 ppm, 30 ppm, 40 ppm, 50 ppm, and 60 ppm) and their corrected absorbances. The report stated that the equation of the line and r² were as follows: y = 0.015066 x -0.154424 r² = 0.9997 The sample they tested gave a corrected reading of 0.417. How much Fe is present in ppm? A) 2.80 B) 17.43 C) 2.60 D) 37.93
A chemist received a report from an analysis involving the iron-phenanthroline method, containing the calibration curve for Fe standards (20 ppm, 30 ppm, 40 ppm, 50 ppm, and 60 ppm) and their corrected absorbances. The report stated that the equation of the line and r2 were as follows: y = 0.015066 x – 0.154424 r2 = 0.9997 The sample they tested gave a corrected reading of 0.417. How much Fe is present in ppm? 2.80 17.43 2.60 37.93
A compound with a molecular weight of 229.61 g/mol was dissolved in 50.0 mL of water. 1.00 mL of this solution was placed in a 10.0 mL flask and diluted to the mark. The absorbance of this diluted solution at 510 nm was 0.472 in a 1.000 cm cuvet. The molar absorptivity of the compound, at 510 nm, is 6,310 M-1 cm-1. Calculate the concentration of the compound in the initial 50.0 mL solution. A. 1.50 x 10-5 M B. 7.48 x 10-5 M C. 7.48 x 10-4 M D. 7.48 x 10-6 M
An ethanol solution of 3.5 mg/100 ml of compound Y (150.0 g/mol) in a 1.00 cm quartz cell has an absorbance (A) of 0.972 at λmax=235 nm. What is its molar extinction coefficient? Report your answer to the correct number of significant figures. Do not include units in your answer. I need to know what is the correct number of sig figs for this question which will determine what the correct answer is.
A 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 units