Macmillan LearningThe selenium content in soil can be determined fluorometrically upon conversion ofthe selenium to the fluorescent product shown, followed by extraction in cyclohexane.Emission from the fluorescent product is observed at 518 nm.aThe selenium content in a 0.147 g soil sample was converted to the fluorescent productand extracted in 50.0 mL of cyclohexane. The method of standard additions was used to determine the selenium content in thesoil sample. Initially, 3.00 mL of the cyclohexane solution were placed in a cuvette for fluorescence determination. Several smalladditions of a 2.66 µg Se/mL standard solution containing the fluorescent product were added to the 3.00 mL solution in thecuvette. The fluorescence was measured at 518 nm. The results are shown in the table.Total added Se standardvolume (µl)0.0020.040.060.080.0Se wt% =50625Fluorescence intensity(arbitrary units)Determine the weight percent (wt%) of selenium in the soil sample and find the absolute uncertainty in the weight percent ofselenium. Report the weight percent and absolute uncertainty with three significant figures.Incorrect54.3164.576.791.1108.3.0021SeIncorrect88

Given: To Calculate: weight percent Se in the soil and the absolute uncertainty in the weight…

Answered: The selenium content in soil can be…

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The selenium content in soil can be determined fluora

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter8: Sampling, Standardization, And Calibration

Section: Chapter Questions

Problem 8.25QAP

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Question

Macmillan Learning
The selenium content in soil can be determined fluorometrically upon conversion of
the selenium to the fluorescent product shown, followed by extraction in cyclohexane.
Emission from the fluorescent product is observed at 518 nm.
a
The selenium content in a 0.147 g soil sample was converted to the fluorescent product
and extracted in 50.0 mL of cyclohexane. The method of standard additions was used to determine the selenium content in the
soil sample. Initially, 3.00 mL of the cyclohexane solution were placed in a cuvette for fluorescence determination. Several small
additions of a 2.66 µg Se/mL standard solution containing the fluorescent product were added to the 3.00 mL solution in the
cuvette. The fluorescence was measured at 518 nm. The results are shown in the table.
Total added Se standard
volume (µl)
0.00
20.0
40.0
60.0
80.0
Se wt% =
50625
Fluorescence intensity
(arbitrary units)
Determine the weight percent (wt%) of selenium in the soil sample and find the absolute uncertainty in the weight percent of
selenium. Report the weight percent and absolute uncertainty with three significant figures.
Incorrect
54.31
64.5
76.7
91.1
108.3
.0021
Se
Incorrect
88

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