A standard solution contains 100 ppm of Fe, which was found to have an absorbance of 0.151 au at 508 nm after the addition of 1,10-phenanthroline, pH 4 buffer, and hydroxylamine. Then, a water sample treated similarly exhibited an absorbance of 0.109 au. Which of the following statements is true? (A) The Fe concentration of the water sample is higher than 100 ppm. (B) The Fe concentration of the water sample is equal to 100 ppm. It is impossible to estimate the Fe content of the water sample from information presented. (D) The Fe concentration of the water sample is lower than 100 ppm.

A standard solution contains 100 ppm of Fe, which was found to have an absorbance of 0.151 au at 508 nm after the addition of 1,10-phenanthroline, pH 4 buffer, and hydroxylamine. Then, a water sample treated similarly exhibited an absorbance of 0.109 au. Which of the following statements is true? (A) The Fe concentration of the water sample is higher than 100 ppm. (B) The Fe concentration of the water sample is equal to 100 ppm. It is impossible to estimate the Fe content of the water sample from information presented. (D) The Fe concentration of the water sample is lower than 100 ppm.

Principles of Instrumental Analysis

7th Edition

ISBN:9781305577213

Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Chapter14: Applications Of Ultraviolet-visible Molecular Absorption Spectrometry

Section: Chapter Questions

Problem 14.6QAP: The accompanying data (1.00-cm cells) were obtained for the spectrophotometric titration 10.00 mL of...

See similar textbooks

Similar questions

3. An antacid tablet, weighing 1.25 g, was dissolved in a 1.0 L volumetric flask to allow for determination of calcium carbonate and magnesium carbonate contents. After preparing the solution, an aliquot of 10.0 ml was transferred to an Erlenmeyer flask containing a buffer solution with pH = 10. This aliquot was then titrated with EDTA 0.0040 mol/L and the average volume spent was 15.01 mL. To measure calcium after precipitation. After the magnesium was fractionated, a second 10.00 mL aliquot of the stock solution was transferred to an Erlenmeyer flask, and the pH of the present solution was adjusted to a value of approximately 13. In EDTA titration, the volume consumed for observation ofthe end point was equal to 13.03 mL. Based on this information,a) Outline the two steps involved, representing the related reactions./5b) Calculate the concentrations of CaCO3 and MgCO3 present in the initialsolution./6c) Calculate the masses of CaCO3 and MgCO3 present in the pellet./6d) Calculate the…
A standard solution contains 100 ppm of Fe, which was found to have an absorbance of 0.151 au at 508 nm after the addition of 1,10-phenanthroline, pH 4 buffer, and hydroxylamine. Then, a water sample treated similarly exhibited an absorbance of 0.109 au. Which of the following statements is true? The Fe concentration of the water sample is higher than 100 ppm. It is impossible to estimate the Fe content of the water sample from information presented. The Fe concentration of the water sample is lower than 100 ppm. The Fe concentration of the water sample is equal to 100 ppm.
A standard solution was put through appropriate dilutions to give the concentrations of iron shown in the table that follows. The iron(II)-1,10-phenanthroline complex was then formed in 25.0-mL aliquots of these solutions, following which each was diluted to 50.0 mL. The following absorbances (1.00-cm cells) were recorded at 510 nm: Calculate the concentration, in ppm, of a sample with an abosrbance of 0.829. Fe(II) concentration (ppm) A510 4.00 0.160 10.0 0.390 16.0 0.630 24.0 0.950 32.0 1.260 40.0 1.580
A 50.00 ml aliquot of a solution containing Ca2+ and Mg2+ was buffered at pH 10 and titrated with 0.0421 M EDTA. The endpoint volume was 44.10 ml. A second aliquot of the same mixture was made strongly basic by the addition of NaOH – this causes the Mg2+ to precipitate as Mg(OH)2. The solution was then titrated with the 0.0421 M EDTA and the endpoint volume was found to be 35.11 ml.
Finely ground mineral (0.9315 g) was dissolved in 25 mL of boiling 4 M HCl and diluted with 175 mL H2O containing two drops of methyl red indicator. The solution was heated to 100C, and 50 mL of warm solution containing 2.0 g (NH4)2C2O4 were slowly added to precipitate CaC2O4. Then 6 M NH3 was added until the indicator changed from red to yellow, showing that the liquid was neutral or slightly basic. After slow cooling for 1 h, the liquid was decanted and the solid transferred to a filter crucible and washed with cold 0.1 wt% (NH4)2C2O4 solution five times until no Cl- was detected in the filtrate upon addition of AgNO3 solution. The crucible was dried at 105C for 1 h and then at 500 ± 25 C in a furnace for 2 h. Ca2+ + C2O42- --> CaC2O4.H2O(s) -->500C CaCO3(s) The mass of the empty crucible was 16.9743 g, and the mass of the crucible with CaCO3(s) was 17.198164 g. Find the wt% Ca in the mineral. a) Why is the unknown solution heated to boiling and the precipitant solution,…
A 50.00 ml aliquot of a solution containing Ca2+ and Mg2+ was buffered at pH 10 and titrated with 0.0418 M EDTA. The endpoint volume was 44.36 ml. A second aliquot of the same mixture was made strongly basic by the addition of NaOH – this causes the Mg2+ to precipitate as Mg(OH)2. The solution was then titrated with the 0.0418 M EDTA and the endpoint volume was found to be 30.02 ml. Calculate the molar concentration of Mg.
A student has a sea water sample which contains Ca2+ ions . Describe briefly how he willdetermine the concentration of Ca2+ ion in the sample using a simple titration. Explain the colourchanges at the endpoint. Which medium is suitable for performing the titration, acidic or basic medium and why?
Aluminium (III) reacts with the Chelating agent HL to give a complex AlL3 that is readily soluble in CHCl3. A spectrophotometric study shows that when a 1.77 x10-4 M aqueous solution of aluminium was extracted with CHCl3 containing 0.01M HL, the analytical concentration of aluminium at pH 4.5 in the two phases were 1.5 x 10-4 M [Al3+]upper) and 2.73 x10-5 M ([AlL3]lower) . What is the distribution coefficient at pH 4.8.
A phenol standard with a concentration of 4.00 ppm has an absorbance of 0.424 at a wavelength of 460 nm using a 1.00-cm cell. A water sample is steam-distilled, and a 50.00-mL aliquot of the distillate is placed in a 100-mL volumetric flask and diluted to volume with distilled water. The absorbance of this solution is found to be 0.394. What is the concentration of phenol (in parts per million) in the water sample?
A solution containing Mg2+ was buffered to pH 9.81 and titrated with EDTA. Eriochrome black T, with p?a1 = 6.3 and p?a2 = 11.6 was used as the indicator. It is a diprotic acid, H2E What is the fraction of the predominant form of eriochrome black T in solution at this pH? (To answer this, report the alpha fraction of the indicator’s most prevalent species at this pH)
An antacid tablet, weighing 1.25 g, was dissolved in a 1.0 L volumetric flask to allow for determination of calcium carbonate and magnesium carbonate contents. After preparing the solution, an aliquot of 10.0 ml was transferred to an Erlenmeyer flask containing a buffer solution with pH = 10. This aliquot was then titrated with EDTA 0.0040 mol/L and the average volume spent was 15.01 mL. To measure calcium after precipitation After the magnesium was fractionated, a second 10.00 mL aliquot of the stock solution was transferred to an Erlenmeyer flask. and the pH of the present solution was adjusted to a value of approximately 13. In EDTA titration, the volume consumed for observation of the end point was equal to 13.03 mL. Based on this information, (a) Outline the two steps involved, representing the related reactions. (b) Calculate the concentrations of CaCO3 and MgCO3 present in the initial solution. (c) Calculate the masses of CaCO3 and MgCO3 present in the pellet. (d) Calculate the…
. An antacid tablet, weighing 1.25 g, was dissolved in a 1.0 L volumetric flask to allow for determination of calcium carbonate and magnesium carbonate contents. After preparing the solution, an aliquot of 10.0 ml was transferred to an Erlenmeyer flask containing a buffer solution with pH = 10. This aliquot was then titrated with EDTA 0.0040 mol/L and the average volume spent was 15.01 mL. To measure calcium after precipitation. After the magnesium was fractionated, a second 10.00 mL aliquot of the stock solution was transferred to an Erlenmeyer flask, and the pH of the present solution was adjusted to a value of approximately 13. In EDTA titration, the volume consumed for observation of the end point was equal to 13.03 mL. Based on this information, a) Outline the two steps involved, representing the related reactions./5 b) Calculate the concentrations of CaCO3 and MgCO3 present in the initial solution./6 c) Calculate the masses of CaCO3 and MgCO3 present in the pellet./6 d) Calculate…