22. To test a spectrophotometer's accuracy, a solution of 60.06 ppm K2C1207 is prepared and analyzed. This solution has an expected absorbance of 0.641 at 350.0 nm. Several aliquots of the solution produce the following absorbance values. 0.640 0.638 0.640 0.639 0.640 0.639 0.638 s there any significant difference between the experimental mean and the expected value at a 99.9% confidence level? Yes because tcal>teritical Yes because tcaltcritical O No because tcal

22. To test a spectrophotometer's accuracy, a solution of 60.06 ppm K2C1207 is prepared and analyzed. This solution has an expected absorbance of 0.641 at 350.0 nm. Several aliquots of the solution produce the following absorbance values. 0.640 0.638 0.640 0.639 0.640 0.639 0.638 s there any significant difference between the experimental mean and the expected value at a 99.9% confidence level? Yes because tcal>teritical Yes because tcaltcritical O No because tcal

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 9.16QAP

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Unrounded Rounded ε∗,L/μmol 0.0259825 0.0260 Heres the data if needed: TZ # Concentration Absorbance at 430 nmnm 1 33.6480 0.931 2 25.2360 0.757 3 16.8420 0.210 4 8.41200 0.137 5 4.20600 0.122
Guanosine has a maximum absorbance of 275 nm. ϵ275= 8400M−1cm−1 and the path length is 1 cm. Using a spectrophotometer, you find the that A275=0.70. What is the concentration of guanosine?
* Question Completion Status: QUESTION 6 Most analytical machines used in science can either measure absorbance of light, like the spectrophotometers used in BioZ 151 and 152 labs, or can measure change in electrical conductance. In order to convert things like absorbance values into concentration data, a linear regression is used. In order to determine nitrite concentration in water samples, nitrite is reacted with several chemicals to produce a purple color. The absorbance of the solution is measured from known amounts of nitrite to produce a standard curve to analyze samples. Use the data in the provided table, or from the linked spreadsheet to make a graph and perform a linear regression using treadline. mg/L NO, Absorbance 0.1 0.183 0.3 0.5 0.7 0.542 0.914 1.298 1.61 In order for this to work, samples must be diluted prior to measurement standard curve. If a sample underwent a 0.02 dilution, and produce an absorbance value of 0.903, what is the resultant concentration of NO2 in mg…
To test a spectrophotometer’s accuracy, a solution of 60.06 ppm K2Cr2O7 is prepared and analyzed. This solution has an expected absorbance of 0.641 at 350.0 nm. Several aliquots of the solution produce the following absorbance values. 0.640    0.638    0.640    0.639    0.640    0.639    0.638 is there any significant difference between the experimental mean and the expected value at a 99.9% confidence level? Question 21 options: Yes because tcal<tcritical Yes because tcal>tcritical No because tcal<tcritical No because tcal>tcritical
A group of students made 5 standard solutions and measured their corresponding absorbance values at a wavelength of 525.0 nm to generate the graph below. Absorbance of Standard Solutions to Find Concentration of Unknown X Solution 0.50 y = 75.9x + 0.0045 R? = 0.9946 0.40 %3D 0.30 0.20 0.10 0.00 0.001 0.002 0.003 0.004 0.005 0.006 Concentration of X (mole/L) The colorless reactants V and W form unknown X from the reaction: 2V + W 5 X A solution is prepared by mixing together the following: Volume 0.0150 M V (mL) Volume 0.0150 M W (mL) 6.00 4.00 This solution reaches equilibrium, and then is placed in a 1.00 cm wide cuvet and inserted into the spectrometer, producing an absorbance reading of 0.275 at a wavelength of 525.0 nm. Calculate Keg for the above reaction, including units. Absorbance
Absorbance at 453 nm 8393939 7 fl. oz./20 ml Beer-Lambert's Law (Spectrophotometry) #1 Fe (aq) + KSCN(s) FESCN "(aq) + K" (aq) 3+ To determine the moles of Fe (aq) in a 100. mL sample of an unknown solution, excess KSCN(s) is added to convert all the Fe (aq) into the dark red species FeSCN"(aq), as represented by the equation above. The absorbance of FESCN"(aq) at different concentrations is shown in the graph below. 2+ 0.50 目0.40 0.30 0.20 01 0. 0. 5 x 10-5 10 x 10-5 Concentration of FESCN2+ (M) If the absorbance of the mixture is 0.20 at 453 nm, haw many moles of Fe (aq) were present in the 100. mL sample? (Assume that any volume change due to adding the KSCN(s) Iis negligible.) 3+, 4x10-4 mol 3 x 104 mol (B) 4x 10-6 mol 3x 10-6 mol
2. ] You make 150.0 mL of a copper(II) sulfate solution but forget to cover it before leaving for the day. The next class, you measure the volume and find that you only have 132.0 mL remaining. You didn’t record the initial concentration, but you measure the absorbance of the remaining solution at 620 nm and find that it is 0.386. You also construct the following calibration curve for CuSO4: Standard solution Abs620 0.50 M 0.424 0.40 M 0.336 0.30 M 0.247 0.20 M 0.159 (refer to image) a. What is the value for k (in Beer’s Law)? Provide a calculation or graph to support your answer. b. What is the concentration of the (remaining) solution? c. What was the concentration of the original solution from the first class? d. If you removed 7.5 mL from the 132.0 mL solution in the process of measuring the absorbance, how much water should you add to obtain the original concentration that you solved for in part (c)?
Five standard chromium (VI) solutions were prepared through serial dilution technique with corresponding absorbance readings at 540 nm wavelength as follows: Absorbance Concentration A1 = 0.650 C1 = 1.9 ppm A2 = 0.712 C2 = 4.0 ppm A3 = 1.370 C3 = 6.0 ppm A4 = 2.050 C4 = 8.0 ppm A5 = 3.423 C5 = 10.0 ppm The sample solution gives an average absorbance reading of 0.713. What is then the concentration of chromium (VI) ion in the sample? (Note: please provide necessary solutions)
Given the following sample concentrations and corresponding absorbances, construct a standard curve of absorbance vs. concentration and determine the molar absorptivity constant. Sample Concentration 15 μΜ 25 μΜ 40 μΜ Absorbance 0.19 0.32 0.49 55 μΜ 0.70
In determining the concentration of a sample X, it was found that it has maximum absorbance at 275 nm. Compound X, has molar absorptivity at 275 nm of 8400 L / mol.cm. Using a spectrophotometer with a 1 cm cuvette, an absorbance of 0.70 was found. What is the concentration of compound X in the sample?
Calculate the path length in centimetres which would give an absorbance of 0.134 of a colored dye with a molar absorptivity of 0.759 L mol-1 cm-1 at a wavelength of 645 nm if the concentration of the dye is 6.82x10-2 M. Report your answer to 3 significant figures.
Blue Blue dye stock solution Absorbance at 630 nm Calibration curve Part 1: 0.1944 M 0.00697 y = 0.0682x A purple solution is prepared by mixing 5.00 mL of the blue dye solution with 6.75 mL of red dye solution. The calibration curve for each color is provided. Part 2 out of 3 (a) Determine the theoretical molar concentration of each dye in the mixture. [Blueltheoretical = 8.27 x 10-2 [Red] theoretical = 1.16 [Bluelexperimental [Redlexperimental " *10-1 M M x 10 (b) Using the absorbance and calibration curve for each dye, calculate the experimental molar concentration of each dye in the mixture. x 10 Red Red dye stock solution Absorbance at 500 nm Calibration curve 0.2015 M 0.00193 y = 0.0170x M M