Given the following data: Molar absorptivity (a) at Molar absorptivity at 460 nm 400 nm Vanadium (V) 145 232 Titanium (Ti) 644 321 A sample mixture consisting of V and Ti only has absorbances of 0.172 at 400 nm and 0.116 at 460 nm in a 1.00 cm cell. Determine the concentrations of the dyes on the mixture solution: (Note this is a simultaneous equation) 1. [ Select ] 2. [ Select ]

Given the following data: Molar absorptivity (a) at Molar absorptivity at 460 nm 400 nm Vanadium (V) 145 232 Titanium (Ti) 644 321 A sample mixture consisting of V and Ti only has absorbances of 0.172 at 400 nm and 0.116 at 460 nm in a 1.00 cm cell. Determine the concentrations of the dyes on the mixture solution: (Note this is a simultaneous equation) 1. [ Select ] 2. [ Select ]

Appl Of Ms Excel In Analytical Chemistry

2nd Edition

ISBN:9781285686691

Author:Crouch

Publisher:Crouch

Chapter12: Spectrochemical Methods

Section: Chapter Questions

Problem 16P

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0 The acid-base indicator HIn undergoes the following reaction in dilute aqueous solution:HIn color1 m H1 1 In2color2The following absorbance data were obtained for a 5.00 3 1024M solution of HIn in 0.1 M NaOH and0.1 M HCl. Measurements were made at wavelengths of 485 nm and 625 nm with 1.00-cm cells.0.1 M NaOH A485 5 0.075 A625 5 0.9040.1 M HCl A485 5 0.487 A625 5 0.181In the NaOH solution, essentially all of the indicator is present as In2; in the acidic solution, it is essentiallyall in the form of HIn.(a) Calculate molar absorptivities for In2 and HIn at 485 and 625 nm.(b) Calculate the acid dissociation constant for the indicator if a pH 5.00 buffer containing a small amountof 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…
What is the concentration (M) of the following compound as measured in a 1.000 cm cuvette: Molar absorptivity constant: 3525 (M*cm)-1 and Absorption: 0.5334 Hint: Use the Beer law to solve this problem Group of answer choices 1.513E-04 1.513E+04 1.513191E-04 1.513191E+04 1.5E-04
One common way to determine phosphorous in urine is to treat the sample after removing the protein with molybdenum (VI) and then reducing the resulting 12-molybdophosphate complex with ascorbic acid to give an intense blue-coloured species called molybdenum blue. The absorbance of molybdenum blue can be measured at 650 nm. A 24-hour urine sample was collected, and the patient produced 1122 mL in 24 hours. A 1.00 mL aliquot of the sample was treated with Mo (VI) and ascorbic acid and diluted to a volume of 50.00 mL A calibration curve was prepared by treating 1.00 mL aliquot of phosphate standard solution in the same manner as the urine sample. The absorbances of the standards and the urine sample were obtained at 650 nm and the following results were obtained. ppm, P aBSORBANCE (A) 1.003.00 0.230 2.00 0.436 3.00 0.638 4.00 0.848 Urine sample 0.518 ffind the slope and intercept, then graph it.
Calculate the absorbance at 280 nm that is expected for a 17 microM solution of peptide GRAYISH, if a 10-cm cuvette is used. For the extinction coefficient, take into account that e280(Trp) = 5690 M-1 cm-1 and e280(Tyr) = 1280 M-1 cm-1.
If the apparent molar absorptivity of cefuroxime sodium is 2.046 × 103 L mol−1 cm−1 in a 1-cm cuvette, at what concentration should the standard and sample solutions be prepared to result to an ideal absorbance value of 0.500? Show your solution.
The following calibration data were obtained by an atomic absorption spectrophotometric (AAS) method for the determination of mercury in an herbal product. (show complete solution) 1. What is the detection limit for the method? 2. What is the limit of quantitation for the method?
What is the molar extinction coefficient at 625 nm for this copper (II) acetate solution? How was it determined? Standard Solution Concentration (M) Absorbance 1 0.025 0.049 2 0.050 0.153 3 0.100 0.242 4 0.200 0.499 5 0.250 0.694
A solution of Tryptophan has an absorbance at 280 nm of 0.54 in a 0.5 cm length cuvette. Given the absorbance coefficient of trp is 6.4 x 103 Lmol-1cm-1. What is the concentration of solution?
Using the absorbance of [FeSCN]+2 at the wavelength of maximum absorption which you obtained in part B, and the diameter of the tube, obtained in part A,calculate the molar extinction coefficient. given info: Concentration of Fe3+ stock solution, C1 = 0.001 M Volume of stock Fe3+ solution pipetted, V1 = 25mL Concentration of diluted stock solution, C2 = 0.0004 M Volume of Fe2+ solution and KSCN (upon mixing) = 10mL Weight of KSCN = 1g The reaction taking place is given as: The reaction taking place is given as: F e 3+ (aq) + SC N − (aq) ⇔Fe [SCN] 2+ (aq) the concentration of [FeSCN]2+ after the mixing of Fe3+ and SCN- is 2.5 x 10-3 M. Moles of [FeSCN]2+ = 2.5 x 10-5 moles Diameter:1.2cm The wavelength at which maximum absorption takes place is = 480 nm
The absorbance of an iron thiocyanate solution containing 0.00500 mg Fe/mL was reported as 0.4900 at 540nm. Calculate the specific absorptivity including units of iron thiocyanate on the assumption that a 0.100 cm cuvette was used.
A dual beam UV-visible spectroscopy was used to determine the levels of Fe(II) in the run-off water of a local mine using the ferrozine assay (i) During a check of the instrument a step-like feature at 360 nm was observed in spectrum of the standard. Suggest what may give rise to this with reference to the instrument configuration and comment on how it may be remedied. (ii) The molar absorptivity of the [Fe(Ferrozine)3]2+ complex is 27900 cm−1 M−1 at 562 nm in aqueous solution (pH 5.5). If the EU maximum contaminant level for Fe is 200 ug /L and the contract required detection limit is 100 ug/L, comment on the suitability of the assay for the detection of iron. (iii) Determine the sample range, in terms of concentration and ppm, of Fe(II) that can be confidently analysed by UV-visible spectroscopy using a 1 cm cuvette. Explain with reference to an appropriate equation and solution phenomena, the origin of the limitations that define this range
A calibration curve for the colorimetric determination of phosphorous in urine is prepared by reacting standard solutions of phosphate with molybdenum(VI) and reducing phosphomolybdic acid complex to produce the characteristic blue color. The absorbance (A) is plotted against the concentration of phosphorous. From the following data, determine the linear least-squares straight line and calculate the concentration of phosphorous in the urine sample. Phosphorous (ppm) 1.00 2.00 3.00 4.00 Unknown urine sample Fluorescence intensity 0.205 0.410 0.615 0.820 0.625