B. The copper concentration in a contaminated salt sample was determined by flame atomic absorption spectrometry. In the analysis, a 10.00-g sample containing an analyte is transferred to a 250-ml volumetric flask and diluted to volume. A series of 10.0 mL of the diluted sample solution was pipetted into each of five 50.0-mL volumetric flasks. Various volumes of a standard containing 12.2 ppm Cu were added to the flasks, and the solutions were then diluted to volume. The corresponding absorbances of each of the solutions are given below: Unknown, mL 10.0 10.0 10.0 10.0 10.0 Standard, mL 0.0 10.0 20.0 30.0 40.0 Absorbance 0.201 0.292 0.378 0.467 0.554 Calculate the copper concentration (a) in the diluted sample solution expressed in ppm Cu, and (b) in the salt sample as percent copper (%Cu).

B. The copper concentration in a contaminated salt sample was determined by flame atomic absorption spectrometry. In the analysis, a 10.00-g sample containing an analyte is transferred to a 250-ml volumetric flask and diluted to volume. A series of 10.0 mL of the diluted sample solution was pipetted into each of five 50.0-mL volumetric flasks. Various volumes of a standard containing 12.2 ppm Cu were added to the flasks, and the solutions were then diluted to volume. The corresponding absorbances of each of the solutions are given below: Unknown, mL 10.0 10.0 10.0 10.0 10.0 Standard, mL 0.0 10.0 20.0 30.0 40.0 Absorbance 0.201 0.292 0.378 0.467 0.554 Calculate the copper concentration (a) in the diluted sample solution expressed in ppm Cu, and (b) in the salt sample as percent copper (%Cu).

Appl Of Ms Excel In Analytical Chemistry

2nd Edition

ISBN:9781285686691

Author:Crouch

Publisher:Crouch

Chapter12: Spectrochemical Methods

Section: Chapter Questions

Problem 12P

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The chromium in an aqueous sample was determined by pipetting 10.0 ml. of the unknown into each of five 50.0-mL volumetric flasks. Various volumes of a standard containing 12.2 ppm Cr were added to the flasks, following which the solutions were diluted to volume. Unknown,mLStandard, mLAbsorbancc 10.00.00.201 10.010.0 0.292 10.020.0 0.378 10.030.0 0.467 10.040.0 0.554 (a) Plot the data using a spreadsheet. (b) Determine an equation for the relationship between absorbance and volume of standard. (c) Calculate the statistics for the least-squares relationship in (b). (d) I)ctcrmine the conccnt ration oÍCr in ppm in the sample. (e) Find the standard deviation of the result in (d).
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(Standard addition) Tooth enamel consists mainly of the mineral calcium hydroxyapatite, Ca10(PO4)6(OH)2. Trace elements in teeth of archeological specimen provide anthropologists with clues about diet and diseases of ancient people. Student at Dankook University measured the trace element strontium (Sr) in enamel from extracted wisdom teeth by atomic absorption spectroscopy. Solutions were prepared with a constant total volume of 10 mL containing 0.750 mg dissolved tooth enamel plus variable concentrations of added standard Sr. Added Standard Sr (ng/mL=ppb) 0 2.50 5.00 7.50 10.00 Emission Signal 28.0 34.3 42.8 51.5 58.6 (a) Make a graph showing the experimental data and the calculated straight line. (b) Find the concentration of Sr in the tooth ennamel in parts per million = μg/mL.
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