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.
(b) An aqueous solution whose concentration is 0.00344 M was analysed using spectrophotometer with a molar absorptivity of 412 cm-1 mo1 L in a cell with a 2.00 cm pathlength. Calculate the absorbance and transmittance for the above solution.
A Dubosq colorimeter consists of a cell of fixed path length and a cell of variable path length. By adjusting the length of the latter until the transmission through the two cells is the same. the concentration of the second solution can be inferred from that of the former. Suppose that a plantdye of concentration 25 μg dm-3 is added to the fixed cell. the length of which is 1.55 em. Then a solution of the same dye. but of unknown concentration. is added to the second cel l. It is found that the same t ransmittance is obtained when the length of the second cel l is adjusted to 1.18 em. What is the concentration of the second solution?
A solution sample, in a 0.50 cm cuvette, exhibits an absorbance of A = 0.84 at lamdamax= 230 nm. Calculate the concentration of the solution if the molar absorption coefficient of the compound at 230 nm is 14 mol–1 dm3 cm–1.
Study and discuss the transient absorption spectra of xanthone in SDS Solution.
An aqueous solution whose concentration is 0.00344 M was analysedusing spectrophotometer with a molar absorptivity of 412 cm-1 mol-1 L ina cell with a 2.00 cm pathlength. Calculate the absorbance andtransmittance for the above solution.
Analysis of two components by visible spectroscopy The absorbances of pure solutions of X (1.00 x 10³ M) and Y (2.00 x 10+ M) at 440 nm and 545 nm in a 1 cm cell are: Ax 40 = 0.374, Ax545= 0.009, Ay,40 = 0.019, Ay,545 = 0,475 a. Calculate the molar absorptivities (e) of X and Y at each wavelength. 440 nm 545 nm E (X) E (Y) b. An mixture of unknown concentration of X and Y ions was analyzed by measuring the absorbance at two wavelengths (440 nm and 545 nm) in a 1 cm cell. The following results are obtained: Auoam - 0.405, As45mm - 0.712 Calculate [X] and [Y] in the mixture.
The molar absorptivity constant of a particular chemical is 3.9 dm3 mol–1 cm–1 . What is the concentration (in Molar) of a solution made from this chemical that has an absorbance of 0.410 with a cell path length of 1.0cm?
A 0.00340 M solution of a substance was analysed using spectrophotometer with a molar absorptivity of 412 cm-1 mol-1 L in a cell with a 3.00 cm pathlength. Calculate the absorbance and transmittance for the above solution.
At 520 nm with a 1.00 cm cell a 8.24 ppm solution of KMnO4 has a transmittance of 0.126. What is the molar absorptivity of KMnO4 at 520 nm?
SA7. Two solutions have identical absorbance value at 350 nm of 0.100 Abs unit. One contains fluorene and the other anthracene. The fluorescence emission intensity measured from the anthracene sample was higher than that measured from the fluorene sample. Explain the fundamental reason for this observation.

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