Concept explainers
(a)
Interpretation:
A calibration curve from the given data should be plotted.
Concept introduction:
A calibration curve or standard curve is a method used in
(b)
Interpretation:
Using the method of least squares, an equation relating absorbance and the concentration of Fe(II) should be developed.
Concept introduction:
For equations,
The slope of the line,
The intercept,
(c)
Interpretation:
The standard deviation of the slope and the intercept should be calculated.
Concept introduction:
Standard deviation about regression,
N − number of points used.
The standard deviation of the slope,
The standard deviation of the intercept,
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Chapter 14 Solutions
Principles of Instrumental Analysis
- The absorbance of a 0.00105% m/v solution of tolbutamide in methanol when measured in a 1 cm path length cell was found to be 0.796 at 228 nm. Calculate the specific absorbance.arrow_forwardThe molar absorptivity (ε) of the FeSCN2+ complex ion is 4700 M-1 · cm-1 at a wavelength of 450 nm. Using a 1-cm sample tube, you measure the absorbance as (2.0x10-1). What is the concentration of FeSCN2+?arrow_forwardMercury(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…arrow_forward
- Calculate the molar absorptivity and absorbance of a 1.00 x 104 M solution, which has atransmittance of 32.1% , when the path length is 2.5 cm at 650 nm. (arrow_forwardAtomic absorption spectroscopy with graphite furnace atomization is an extremely sensitive technique. The standard addition method is used with this technique to determine the concentration of copper in urine. A 20.00 mL sample of urine is spiked with 1.00 mL of 300. ppb Cu²+ and this mixture gives a response of 0.168. Another 1.00 mL aliquot of 300. ppb Cu²+ is added to this mixture and gives a reading of 0.235Determine the concentration of copper in the urine samplearrow_forwardThe absorbances of solutions containing K2CrO4 in 0.05 M KOH were measured in a 1.0-cm cell of 375 nm. The following results were obtained: Calculate the concentration of K2CrO4 (g/L) if the A is 0.550.arrow_forward
- At 580 nm, the wavelength of its maximum absorption, the complex Fe(SCN)2+ has a molar absorptivity of 7.00 X 103 L mol-1 cm-1. Calculate (a) the absorbance of a 2.50 X 10-5 M solution of the complex at 580 nm in a 1.00-cm cell. (b) the absorbance of the solution in which the concentration of the complex is twice that in part (a) (c) the transmittance of the solutions described in parts (a) and (b) (d) the absorbance of a solution that has half the transmittance of that described in part (a) answer letter d pleasearrow_forwardAt 580 nm, the wavelength of its maximum absorption, the complex Fe(SCN)2+ has a molar absorptivity of 7.00 X 103 L mol-1 cm-1. Calculate (a) the absorbance of a 2.50 X 10-5 M solution of the complex at 580 nm in a 1.00-cm cell. (b) the absorbance of the solution in which the concentration of the complex is twice that in part (a) (c) the transmittance of the solutions described in parts (a) and (b) (d) the absorbance of a solution that has half the transmittance of that described in part (a)arrow_forwardA dual beam UV-visible spectroscopy was used to determine the levels of Fe(II) in the run-off water of a local mine using the ferrozine assay (i) During a check of the instrument a step-like feature at 360 nm was observed in spectrum of the standard. Suggest what may give rise to this with reference to the instrument configuration and comment on how it may be remedied. (ii) The molar absorptivity of the [Fe(Ferrozine)3]2+ complex is 27900 cm−1 M−1 at 562 nm in aqueous solution (pH 5.5). If the EU maximum contaminant level for Fe is 200 ug /L and the contract required detection limit is 100 ug/L, comment on the suitability of the assay for the detection of iron. (iii) Determine the sample range, in terms of concentration and ppm, of Fe(II) that can be confidently analysed by UV-visible spectroscopy using a 1 cm cuvette. Explain with reference to an appropriate equation and solution phenomena, the origin of the limitations that define this rangearrow_forward
- at 580 nm, which is the wavelength of its maximum absorption the complex Fe(SCN)2+ has a molar absoptivity of 7.00x10^3 L cm-1 mol-1. Determine the absorbance of a 3.50 x10^-5 M solution of the complex at 580 nm in a 1 cm cell Express in 3SFarrow_forwardThe determination of iron in wines was carried out by atomic absorption spectrophotometry, using the standard addition method. To do this, 10 mL of wine were placed in five 50 mL volumetric flasks; then 0, 5, 10, 15 and 20 mL of a 10 ppm iron standard solution were added to each of them. Next, they were gauged with distilled water and the absorbance was measured, obtaining the values of 0.040, 0.062, 0.081, 0.102 and 0.125 respectively. Calculate the regression parameters and obtain the iron concentration in the wine, in µg / mL.arrow_forward1. Define: spectrochemical methods, spectroscopy, spectrometry, spectrometer, and spectrophotometer. 2. What is specific about the general analytical strategy for spectrochemical analysis methods comparedto instrumental analysis in general? 3. What is meant by the dual nature of light?arrow_forward
- Principles of Instrumental AnalysisChemistryISBN:9781305577213Author:Douglas A. Skoog, F. James Holler, Stanley R. CrouchPublisher:Cengage Learning