The IR (infrared) spectra of two pure compounds (0.010 M compound A in solvent and 0.010 M compound B in solvent) aregiven. The pathlength of the cell is 1.00 cm. The y-axis in the spectra is transmittance rather than absorption, so that thewavenumbers at which there is a dip in the curve correspond to absorption peaks.A mixture of A and B in unknown concentrations gave a percent transmittance of 49.8% at 2976 cm¹ and 44.9% at 3030 cm-1Wavenumber0.010 M A0.010 M BUnknown3030 cm-135.0%93.0%44.9%2976 cm-¹76.0%42.0%49.8%What are the concentrations of A and B in the unknown sample?Transmittance (%)1009080706050402976 cm-1303030 cm-120Pure A10Pure B030402990Wavenumber (cm-1)29402890

To solve the concentrations of A and B in the unknown sample, create two equations from the data in…

Answered: The IR (infrared) spectra of two pure…

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter26: Molecular Absorption Spectrometry

Section: Chapter Questions

Problem 26.32QAP

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Potassium dichromate (K2Cr2O7) and potassium permanganate (KMnO4) give overlapping UV-Vis absorption spectra in 1 M sulphuric acid. K2Cr2O7 shows an absorption maximum at 440 nm and KMnO4 shows the absorption maximum at 545 nm . An unknown sample solution containing a mixture of K2Cr2O7 and KMnO4 was analyzed using a 1-cm cell and the absorbance values at these two wavelengths were as follows: A440 = 0.515 and A545 = 0.835 The absorbance values for standard solutions of K2Cr2O7 (1.00 x 10-3 M) and KMnO4 (2.00 x 10-4 M) in 1 M sulphuric acid using the same 1 cm cell were as follows: Calculate the concentrations of K2Cr2O7 and KMnO4 in the unknown sample.
Potassium dichromate and potassium permanganate have overlapping absorptionspectra in 1M H2SO4 . K2Cr2O7 has an absorption maxima at 440 nm, and KMnO 4 has a band at 545nm (the maximum is actually at 525 nm, but the longer wavelength is generally used whereinterference from K2C2O7 is less). A mixture is analyzed by measuring the absorbance at these twowavelengths with the following results: A 440 =0.405, A 545 =0.712 in a 1-cm cell. The absorbances ofpure solutions of K2Cr2O7 (1x10 -3 M) and KMnO 4 (2.00x10 -4 M) in 1 M H 2 SO 4 , using the same cell gavethe following results: A Cr,440 = 0.374, A Cr,545 = 0.009, A Mn,440 =0.019, A Mn,545 = 0.475. Calculate theconcentrations of dichromate and permanganate in the sample solution.
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.
(a) A sample of body serum is to be analysed for sodium by flame emission spectroscopy. 1.00cm3 aliquot of serum was pipetted into each of two 50.0 cm3 volumetric flasks. The firstflask was diluted to volume with deionised water. The absorbance of this first solution was0.350. To the second flask 10.0 cm3 of a 25.0 ppm sodium standard was added and theflask made up to volume with deionised water. The absorbance of this second solution was0.720.(i) Calculate the concentration of the sodium in the body serum in mg dm–3
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 extinction coefficient (ɛ) of 23,150 at Amax=235 nm. What is the expected absorption (A)? Report your answer to the correct number of significant figures.,
Which of the following statement is incorrect? The quality of grating of the monochromator affects the resolution of two closely spaced wavelengths in a spectrum. OICP (Inductively coupled plasma) is commonly used in atomic emission spectrometry. Cuvette is generally used for atomic absorption spectrometry (AAS) as the sample cell. The measurement in fluorescence spectrometry is generally more sensitive than absorption spectrometry.
(a) You measure the percent transmittance of a solution containing chromophore X at 400nm in a 1-cm path length cuvette and find it to be 50%. What is the absorbance of this solution? (b) What is the molar absorptivity of chromophore X if the concentration of X in the solution measured in question (a) is 0.5mM? (c) What is the concentration range of chromophore X that can be assayed if, when using a sample cell of path length 1, you are required to keep the aborbance between 0.2 and 0.8?
When measured in a 1.00 cm cuvette, a 4.1x10M solution of species X exhibited absorbances of 0.1025 and 0.533 at 530 nm and 325 nm, respectively. A8.20x10 M solution of species Y gave absorbances of 0.230 and 0.508 at 530 nm and 325 nm, respectively. Both species were dissolved in the same solvent, and the solvent's absorbance was 0.000 and 0.000 at 530 nm and 325 nm, respectively, in a 1 cm cuvette. Calculate the concentrations of X and Y in an unknown solution that yielded absorbance data of 0.683 at 530 nm and 1.351 at 325 nm in a 1.0 em cuvete O A.X-4.20 x10 M Y=3.20 x104 M OBX-1.25 X10M Y420 x10-SM OCX-3.75x1oM Y-1 A10M OD.X-3.80 x 10M Y=2.10x10M
A student prepared several solutions of an unknown molecule, each at a different concentration. The absorbance of each solution was measured at 630 nm with a path length of 0.760 cm. The student then plotted the absorbance of each sample vs. its concentration (in uM), and found a best-fit line of y = 0.00626x + 0.00732. Calculate the molar absorptivity of the unknown molecule (in M-1 cm-1).
Mercury(II) forms a 1:1 complex with triphenyltetrazolium chloride that exhibits an absorption maximum at 255 nm. The mercury(II) in a soil sample was extracted into an organic solvent containing an excess of TTC , and the resulting solution was diluted to 100.0 mL in a volumetric flask. Five-milliliter aliquots of the analyte solution were then transferred to six 25-mL volumetric flasks. A standard solution was then prepared that was 5*10^-6 M in . Volumes of the standard solution shown in the table were then pipetted into the volumetric flasks, and each solution was then diluted to 25.00 mL. The absorbance of each solution was measured at 255 nm in 1.00-cm quartz cells. Please solve and explain these questions: A.) Enter the given data pictured above into a spreadsheet and show the correct standard additions plot B.) Determine the slope and the intercept of the line C.)Determine the standard deviation of the slope and the intercept. D.) Calculate the concentration of Hg(II) in the…
3) A compound, X, with a molecular weight of 292.16 g/mol was dissolved in a 5.00 mL volumetric flask and diluted to the mark. A 1.00 mL aliquot of this was withdrawn, placed into a 10.00 mL volumetric flask and diluted to the mark. The absorbance at 340 nm was 0.427 in a 1.000 cm cuvette. The molar absorptivity of X at 340 nm is 6130 M-¹ cm-¹ a) Using Beer's Law, what is the [X] (concentration in molarity) for the diluted solution in the cuvet ? mmmmm b) Use the dilution equation (McVc = MdVa) to calculate [X] in the original 5.00 mL flask. c) How many milligrams of X was used in the original solution ? (Find total moles X using original concentration and original volume - and then use the molar mass to go from moles to grams and then milligrams)
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.

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