Can you answer this 17:55 Mon, 29 Apr MProblem Sheet 4 Electroanalysis_918840047 - SavedInsert Draw Layout Review ViewFileHomeI UX, More FormattingE E⭑A3. The calibration data for the determination of lead levels in fruit juices by a differential pulsepolarography method is shown below.[Pb]/ugL-1Current/μA00.000 0.118510203040500.240 0.507 0.713 0.9811.183When these data were plotted using linear regression a correlation coefficient, R2, of 0.9988and a line of best fit were obtained;y= 0.0239x+0.005Use this information to determine the lead levels in the unknown sample, which had beendiluted by a factor of 25, from the following replicate measurements; 0.475, 0.481, 0.486,0.479 and 0.484 μA.65%KC

I think the equation given is trying to predict the Absorption level rather than the lead…

Answered: 17:55 Mon, 29 Apr M Problem Sheet 4…

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

Chapter17: Applications Of Infrared Spectrometry

Section: Chapter Questions

Problem 17.9QAP

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The chromium in an aqueous sample was determined by pipetting 10.0 ml. of the unknown into each of five 50.0-mL volumetric flasks. Various volumes of a standard containing 12.2 ppm Cr were added to the flasks, following which the solutions were diluted to volume. Unknown,mLStandard, mLAbsorbancc 10.00.00.201 10.010.0 0.292 10.020.0 0.378 10.030.0 0.467 10.040.0 0.554 (a) Plot the data using a spreadsheet. (b) Determine an equation for the relationship between absorbance and volume of standard. (c) Calculate the statistics for the least-squares relationship in (b). (d) I)ctcrmine the conccnt ration oÍCr in ppm in the sample. (e) Find the standard deviation of the result in (d).
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?
An atomic absorption method for the determination of the amount of iron present in used jet engine oil was found from pooling 30 triplicate analyses to have a standard deviation s = 3.1 µg Fe/mL. If s is a good estimate of o, calculate the 95 and 99% confidence intervals for the result 21.7 µg Fe/mL if it was based on the following criteria. (a) a single analysis 95% confidence interval= 21.7 + 99% confidence interval = 21.7 + (b) the mean of two analyses 95% confidence interval = 21.7 + 99% confidence interval= (c) the mean of six analyses 21.7 ± 95% confidence interval = 21.7 + 99% confidence interval= 21.7 + μg Fe/mL μg Fe/mL μg Fe/mL μg Fe/mL μg Fe/mL μg Fe/mL
You obtained the following raw data when setting up a Bradford standard curve: BSA (mg/ml) Absorbancy 595nm 0 0.225 1 0.310 2 0.420 3 0.510 4 0.610 5 0.720 6 0.810 7 0.915 8 0.950 9 0.980 10 0.990 After blanking against a bradford-dH2O sample, the protein concentration of an unknown sample was determined using the same method and an absorbancy of 0.523 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).
Exactly 5.00 mL aliquots of a solution containing analyte X were transferred into 50.00-mL volumetric flasks and the pH of the solution is adjusted to 9.0. The following volumes of a standard solution containing 2.00 µg/mL of X were then added into each flask and the mixture was diluted to volume: 0.000, 0.500, 1.00, 1.50 and 2.00 mL. The fluorescence of each of these solutions was measured with a fluorometer, and the following values were obtained: 3.26, 4.80, 6.42, 8.02 and 9.56, respectively. ii. Using relevant functions in Excel, derive a least-squares equation for the data, and use the parameters of this equation to find the concentration of the phenobarbital in the unknown solution.
The absorbance value for the Standard was 0.625 and [FeSCN^ 2+ ] std is 2.00E 4M Calculate the [FeSCN^ 2+ ] in the equilibrium mixture, report the answer to the correct significant figures. The absorbance of the equilibrium solution was 0.451
Suppose you measure the absorbance of a yellow dye solution in a 1.00 cm cuvette (b=1.00 cm). The absorbance of the solution at 427 nm is 0.29 . If the molar absorptivity of yellow dye at 427 nm is 27400 M- cm-1, what is the concentration of the solution in M? Type answer: < ВАСК Question 6 of 6 REVIEW étv A 80 F3 F9 F2
Given: A: y = 0.0987x+4*(-5) B: y = 0.0514x +0.0011 from a plot of absorbance versus concentration (u M) Find: selectivity coefficient between analytes A and B
The kinetics of hydrolysis of acetylsalicylic acid (aspirin) under certain conditions of temperature, pH, type of buffer and strength ionic, can be followed by multicomponent spectrophotometry. When performing a calculation of optical constants, the following data were obtained: Solution C. mg/100 mL A in λ (276nm) A in λ (290nm) Ac. acetylsalicylic ( AAS) 0.202 0.102 0.031 Ac. salicylic (AS) 0.198 0.158 0.101 Reaction: AAS + H2O → AS + CH3COOH In a kinetic study, after a certain time, 1 mL of the solution was taken from the reactor and diluted to 10 mL with water. distilled. Then when proceeding to the spectrophotometric measurement, the last solution presented the absorbances of 0.244 and 0.102 for the lengths of 276 and 290 nm respectively. What are the concentrations of ASA and AS in mg/L, at that instant in the reactor? Note: Acetic acid does not absorb at either wavelength.
The accuracy of a spectrophotometer can be evaluated by preparing a solution of 60.06-ppm K2Cr2O7 in 0.0050 M H2SO4 and measuring its absorbance at a wavelength of 350 nm using a cell with a pathlength of 1.00 cm. The absorbance should be 0.640. What is the molar absorptivity of K2Cr2O7 at this wavelength?
Llë 4 A (0.002M) Cu2+ solution gave an absorbance of O.50 at 560 nm in a 1.0 cm :cell. The molar absobitivity of solution is equel * 2.24 O 250 1120 O 0.004
In spectrophotometric analysis, the relationship between the absorbance A and the analyte's concentration C is: A = ebC + Ablank What is the molar extinction coefficient I and its absolute uncertainty if A is 0.68 ± 0.06; Ablank is 0.06 ± 0.01; b is 1.00 cm; and C is (0.45 ± 0.03)x10-5 mol/L?

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