For the experiment this week, you'll use the relationship between FeSCN²+ absorbance and concentration. Suppose you find that the FeSCN2+ has the following calibration curve. Absorbance Absorbance vs. Concentration of Fe(SCN)²+ 0.8 0.6 0.4 0.2 0 0.00000 0.00005 0.00010 0.00015 0.00020 [Fe(SCN)²+] (M) Suppose you measure the absorbance of an unknown FeSCN2+ solution and find its absorbance to be 0.552. What is the molar concentration of FeSCN2* in the unknown solution? Hint: if you're not sure how to solve this, watch the videos on the Pre-Lab Watch: Concept Videos page. O 0.577 M y=3707.5x-0.0245 R²=0.9989 0.528 M O 0,000142 M O 0.000155 M

For the experiment this week, you'll use the relationship between FeSCN²+ absorbance and concentration. Suppose you find that the FeSCN2+ has the following calibration curve. Absorbance Absorbance vs. Concentration of Fe(SCN)²+ 0.8 0.6 0.4 0.2 0 0.00000 0.00005 0.00010 0.00015 0.00020 [Fe(SCN)²+] (M) Suppose you measure the absorbance of an unknown FeSCN2+ solution and find its absorbance to be 0.552. What is the molar concentration of FeSCN2* in the unknown solution? Hint: if you're not sure how to solve this, watch the videos on the Pre-Lab Watch: Concept Videos page. O 0.577 M y=3707.5x-0.0245 R²=0.9989 0.528 M O 0,000142 M O 0.000155 M

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 9.1QAP

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For the experiment this week, you'll use the relationship between FeSCN2+ absorbance and concentration. Suppose you find that the FeSCN2+ has the following calibration curve. Absorbance Absorbance vs. Concentration of Fe(SCN)²+ 0.8 0.6 0.4 0.2 0 0.00000 0.00005 0.00010 0.00015 0.00020 [Fe(SCN)²+] (M) Suppose you measure the absorbance of an unknown FeSCN2+ solution and find its absorbance to be 0.552. What is the molar concentration of FeSCN2* in the unknown solution? Hint: if you're not sure how to solve this, watch the videos on the Pre-Lab Watch: Concept Videos page. 0.577 M O 0.528 M y=3707.5x -0.0245 R² = 0.9989 0.000142 M O 0.000155 M
6. Blue Blue dye stock solution 0.293 M Absorbance at 630 nm 0.00265 Calibration curve y = 0.0833x A solution is prepared by diluting 2.79 mL of the blue dye stock solution to 25.00 mL. The measured absorbance for the prepared solution is listed in the data table. (a) What is the theoretical molar concentration? [Blue]theoretical x 10 |M (b) What is the experimental molar concentration? [Blue]experimental x 10 M (c) What is the percent error? Percent error (blue) = %
.Q1. To determine the concentrations (mol/L) of Co(NO3)2 (A) and Cr(NO3)3(B) in an unknown sample, the following representative absorbance data wereobtained.A (mol/L) B (mol/L) 510nm 575nm5×10−1 0 0.714 0.0970 6×10−2 0.298 0.757Unknown Unknown 0.671 0.330Measurements were made in 1.0 cm glass cells.i. Calculate the four molar absorptivities: ∈A(510), ∈A(575), ∈B(510) and ∈B(575).ii. Calculate the molarities of the two salts A and B in the unknown.
"[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?
A mixture is prepared by combining 10.72 mL of 2.52 x 10-3 M Fe(NO3)3 with 10.00 mL of 1.76 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 2.25 x 10-4 M.Complete the following ICE table Fe3+ + SCN- ⇌ FeSCN2+ initial (M) (A) (B) (C) change (M) (D) (E) (F) equilibrium (M) (G) (H) (I) What is the value of Kc?
4. To analyze the Cu(NO3)2 unknown solution in Part 3, your group constructed a plot of absorbance vs. concentration, commonly called a calibration curve or standard curve. The absorbance at the top of the peak (i.e., at the wavelength of maximum absorbance) was chosen for these measurements. What is the potential advantage of using the wavelength of maximum absorbance, rather than some other wavelength? Can you think of a situation in which you might want to choose a different wavelength? (Hint: Scientists often do not have the luxurý of analyzing pure substances dissolved in distilled water!)
5. A solution of certain dye has a calibration graph shown below when measured at 425 nm in 1.00cm cells. A sample of the dye with an unknown concentration has an absorbance of 0.733. Determine the molar absorptivity of the dye at 425 nm and the concentration of the dye in the unknown solution. Absorbance vs. Concentration 1.200 1.100 1.000 0.900 0.800 0.700 0.600 0.500 0.400 1.50E-05 2.50E-05 3.50E-05 4.50E-05 5.50E-05 6.50E-05 Dye Concentration (Mol/L)
We can determine the copper(II) ion content of a sample using spectrophotometry. The following data was collected. Construct a calibration plot and determine the slope. Absorbance 0.065 0.205 0.338 0.474 0.598 2.3 x 10-3 3.3 x 104 3.1 x 10-5 3.3 x 10-2 [Cu²+], M 2.00E-06 6.00E-06 1.00E-05 1.40E-05 1.80E-05
Show a sample calculation of how you converted your initial (t = 0) absorbance reading into a concentration. Copy and paste your three graphs below. Sample graph titles: “Determination of whether n = [insert order]”. Red Time (min) A 0 0.617 10 0.536 20 0.456 30 0.375 40 0.294 50 0.214 60 0.133 εb (L/mol) 79.1 Write what is the differential rate law. Predict how fast the reaction would go if the original concentration were tripled. Explain your logic. Use the integrated rate law to predict the concentration at 75 min. Show your calculation here. Calculate the half-life of the reactant at 75 min. Show your work here.
A student makes a Beer's Law plot of A vs [Fe(SCN)2+] in the first part of the equilibrium constant lab, and gets the following information from the trendline. y = 50.7x R² = 0.9999 If the student measures a absorbance of 0.167 for a solution in the second part of the lab, what equilibrium concentration of [Fe(SCN)²+ would be reported?
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
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