Page 20 - Instrumental Analysis - Pharm D Clinical- 07-PA403

UV-visible Spectrophotometry

4- A 7.50 x 10–5 M solution of potassium permanganate has a
transmittance of 36.4% when measured in a 1.05 cm cell at a
wavelength of 525 nm . Calculate A and ε of this solution.
T = 36.4/100 = 0.364
A = – log T = – log 0.364 = – (– 0.439 ) = 0.439
A 0.439
ε = ──── = ──────────── = 5574.6 L mol–1 cm–1 b c
1.05 x 7.50 x 10–5

5- Beryllium (II) forms a complex with acetyl acetone (MW = 166.2).
Calculate the molar absorptivity of the complex given that a 1.34 ppm
solution has a transmittance of 55.7% when measured in a 1.00 cm
cell at 295 nm .

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6- A 5.00 x 10–4 M solution of an analyte is placed in a sample cell with
a pathlength of 1.00 cm. When measured at a wavelength of 490
nm, the solution absorbance is 0.338. What is the analyte molar
absorptivity at this wavelength?

7- A solution containing 4.48 ppm KMnO4 (MW = 158) exhibits 85.9 %T
in a 1.00 cm cell at 520 nm. Calculate the molar absorptivity of
KMnO4 at this wavelength.

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