Following the experimental procedure, a student combined 5.00 mL of 0.0020 M Fe3+ and 1.00 mL of 0.0020 M SCN- with 4.00 mL of water to create their Trial 1 solution. The student used their spectrophotometer to measure the absorbance of the reaction mixture and recorded an absorbance of 0.095. Find the following: Hint: The extinction coefficient of FeSCN2+ is 4,630 M-1*cm-1 and the cuvettes we use have a path length of 1.0 cm. The equilibrium concentration of Fe3+: M (give as decimal to nearest 0.000 001 M) The equilibrium concentration of SCN-: M (give as decimal to nearest 0.000 001 M) The equilibrium constant K: (give to nearest tens place)

Following the experimental procedure, a student combined 5.00 mL of 0.0020 M Fe3+ and 1.00 mL of 0.0020 M SCN- with 4.00 mL of water to create their Trial 1 solution. The student used their spectrophotometer to measure the absorbance of the reaction mixture and recorded an absorbance of 0.095. Find the following: Hint: The extinction coefficient of FeSCN2+ is 4,630 M-1*cm-1 and the cuvettes we use have a path length of 1.0 cm. The equilibrium concentration of Fe3+: M (give as decimal to nearest 0.000 001 M) The equilibrium concentration of SCN-: M (give as decimal to nearest 0.000 001 M) The equilibrium constant K: (give to nearest tens place)

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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Following the experimental procedure, a student combined 5.00 mL of 0.0020 M Fe3+ and 1.00 mL of 0.0020 M SCN- with 4.00 mL of water to create their Trial 1 solution. The student used their spectrophotometer to measure the absorbance of the reaction mixture and recorded an absorbance of 0.095. a. The initial concentration of Fe3+: M (give to nearest 0.0001 M) b. The initial concentration of SCN-: M (give to nearest 0.0001 M) c. The equilibrium concentration of FeSCN2+: (give as decimal to nearest 0.000 001)Hint: The extinction coefficient of FeSCN2+ is 4,630 M-1*cm-1 and the cuvettes we use have a path length of 1.0 cm. d. The equilibrium concentration of Fe3+: M (give as decimal to nearest 0.000 001 M) e. The equilibrium concentration of SCN-: M (give as decimal to nearest 0.000 001 M) f. The equilibrium constant K: (give to nearest tens place)
(Standard addition) Tooth enamel consists mainly of the mineral calcium hydroxyapatite, Ca10(PO4)6(OH)2. Trace elements in teeth of archeological specimen provide anthropologists with clues about diet and diseases of ancient people. Student at Dankook University measured the trace element strontium (Sr) in enamel from extracted wisdom teeth by atomic absorption spectroscopy. Solutions were prepared with a constant total volume of 10 mL containing 0.750 mg dissolved tooth enamel plus variable concentrations of added standard Sr. Added Standard Sr (ng/mL=ppb) 0 2.50 5.00 7.50 10.00 Emission Signal 28.0 34.3 42.8 51.5 58.6 (a) Make a graph showing the experimental data and the calculated straight line. (b) Find the concentration of Sr in the tooth ennamel in parts per million = μg/mL.
1. In using the spectrophotometer PD 303, why is there a need to use water as blank when measuring the absorbance of each solution
Exactly 10.00-mL aliquots of a solution containing phenobarbital were measured into 50.00-mL volumetric flasks and made basic with KOH. The following volumes of a standard solution of phenobarbital containing 2.000μg/mL of phenobarbital were then introduced into each flask and the mixture was diluted to volume: 0.000, 0.500, 1.00, 1.50, 2.00 mL. The fluorescence of each of these solutions was measured with a fluorimeter, which gave values of 3.26, 4.80, 6.41, 8.02, 9.56, respectively. a. plot the data. b. derive a least squares equation for the data plotted in (a). c. find the concentration of phenobarbital from the equation in (b). d. calculate a standard deviation for the concentration obtained in (c).
Seawater was spiked with phosphate to achieve a quantifiable range of phosphate concentrations by the spectrophotometer. What components of the spectrophotometer or sample preparation could be changed that would improve detection limits?
Sally obtains a standard calibration curve for their assigned food dye by plotting absorbance versus concentration (in M) of known solutions and finds the following slope and intercept: y = 1.585x + 0.041 Sally finds that her original Kool-aid sample is too concentrated, so they dilute it by transferring 4.00 mL of the original Kool-aid sample into a new container and diluting to a total volume of 27.00 mL. If the absorbance of the dilute Kool-aid sample at the appropriate wavelength for their assigned dye is 0.931, determine the concentration (in M) of the assigned food dye in the original Kool-aid sample. Report your answer with three places after the decimal.
Nitrite ion, NO2-, is a preservative for bacon and other foods, but it is potentially carcinogenic. A spectrophotometric determination of NO2- makes use of the following reactions: A 5.00 cm cell was used to measure absorbance. Here is an abbreviated procedure for the determination. 1. To 50.0 mL of unknown solution containing nitrite is added 1.00 mL of sulfanilic acid solution. 2. After 10 min, 2.00 mL of 1-aminonapthalene solution and 1.00 mL of buffer are added. 3. After 15 min, the absorbance is read at 520 nm in a 5.00-cm cell. The following solutions were annaylzed: A. 50.0 mL of food extract known to contain no nitrite(that is a neglible amount); final absorbance =0.153 B. 50.0 mL of food extract suspected of containg nitrite ; final absorbance= 0.622 C. Same as B, but with 10 microliters of 7.50x10^-3 M NaNO2 added to the 50.0 mL sample; final absorbance= 0.967 a) Calculate the molar absorptivity of the colored product. Remember that a 5.00 cm cell was used b) How many…
What is the purpose of reference beam in the double-beam spectrophotometer shown in Figure 20-1? Select all the correct answers. a)To correct for changes in source light intensity as a function of time b)to correct for changes in intensity of the light source as a function of wavelength c)to correct of scattering of light off the surface of the sample cuvette d)to correct for absorbance of the solvent e)to correct for changes in detector signal as a function of wavelength
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.
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.
1. at what wavelength was Pb determined? 2. What is the slope of the calibration curve? 3. What is the y-intercept of the calibration curve? 4. The researcher determined the Pb content of water sample from a river suspected to be contaminated with Pb from a nearby factory by complexing with cyanidine and the absorbance measured was 0.405. What is the lead content of the water sample?
one: Topic Molecular Spectroscopy (16 marks) You were given an unknown mixture that contains two metal salts (A) Co(NO3)2 and (B) Cr(NO3)2 and requested to determine their concentration. The following representative information about the absorbance data were also provided. Measurements were made in a 1.0 cm quartz cells. Pure A (mol/l) Pure B (mol/l) 0 Abs @510 nm Abs @575 nm 1.5 x 101 0 6 x 102 Unknown conc in mixture 0.714 0.097 0.298 0.757 Unknown conc in mixture 0.671 0.330 How would you go about calculating the concentration of the two salts?