Which of the following will cause no change in the amount of Fe calculated from the results of an iron-phenanthroline analysis? (A) No added hydroxylamine B All of the given choices will cause a change in the calculated Fe content of the sample Using a pH 10 buffer D Using 0.5% w/v 1,10-phenanthroline instead of 0.1% w/v.

Which of the following will cause no change in the amount of Fe calculated from the results of an iron-phenanthroline analysis? (A) No added hydroxylamine B All of the given choices will cause a change in the calculated Fe content of the sample Using a pH 10 buffer D Using 0.5% w/v 1,10-phenanthroline instead of 0.1% w/v.

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter17: Complexation And Precipitation Reactions And Titrations

Section: Chapter Questions

Problem 17.33QAP

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b. EDTA cannot be used as a primary standard always. When can EDTA be used as a primarystandard ? Give reason why EDTA is used in complexometric titrations.
A 1.000-g sample containing bromide was dissolved in sufficient water to give 100.0 mL. A 50.00 mL aliquot was measured and after acidification, silver nitrate was introduced to precipitate AgBr, which was filtered, washed, and then dissolved in an ammoniacal solution of potassium tetracyanonickelate(II): Ni(CN)42- + 2AgBr(s) → 2Ag(CN)2- + Ni2+ + 2Br-Nickel ion required 11.70 mL of 0.002146 M EDTAWhat is the percentage of NaBr (102.894) in the 1.000 g sample?
Chromel is an alloy composed of nickel, iron and chromium.A 0.6472 g sample was dissolved and diluted to 250 mL. When a50 mL aliquot of 0.05182 M EDTA was mixed with an equal volumeof the diluted sample and all the three ions were chelated, a 5.11 mLback titration with 0.06241 M copper (II) was required.The chromium in a second 50 mL aliquot was masked through theaddition of hexamethylenetetramine, titration of the Fe and Nirequired 36.28 mL of 0.05182 M EDTA.Iron and chromium were masked with pyrophosphate in a third50 mL aliquot and the nickel was titrated with 25.91 mL of theEDTA solution.Calculate the percentage of nickel, chromium and iron in thealloy.
Chromium (III) ion was complexed with EDTA and determined via back-titration. Given the following data, compute for %CrCl3(MM=158.35) in a 2.63 g sample. Conc. of EDTA titrant: 0.0103 MVolume used: 5.00 mLConc. of Zn2+ back titrant: 0.0112 MVolume used: 1.32 mL
An EDTA solution was allowed to react with Pb²⁺ to produce 0.25 M PbY²⁻, 2.67×10⁻⁸ M Pb²⁺ and an excess of 0.10 M at equilibrium (K = 1.1×10⁸). What will be the α₄ value under these conditions?
What conditions must be followed to perform complexometric titration?A. presence of a catalystB. low temperatureC. [metal-EDTA] complex should be more stable than [metal-indicator] complexD. always add an EDTA solution to the analyzed solution and not vice versa
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 second calibration standard solution of an iron(III) salicylate complex was prepared in two steps. First, 10.0 mL of a 0.100 M stock solution was added to 90.0 mL of solvent to make 100.0 mL of the first calibration standard solution and, secondly, 80 mL of that first calibration solution plus 20.0 mL of solvent were mixed to make the second calibration standard. What is the concentration of the second calibration standard solution?
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…
Which of the following statements is true regarding permanganimetry? a) Permanganate solution can oxidize water which is catalyzed by the presence of manganese dioxide or manganese ion. b) The light pink endpoint color for permanganimetry tends to fade with time due to the catalytic reaction. c) Standardization of the permanganate titrant is carried out at elevated temperature with sodium oxalate. d) all of these e) none of these
A 1.000-g sample containing bromide was dissolved in sufficient water to give 100.0 mL. A 50.00 mL aliquot was measured and after acidification, silver nitrate was introduced to precipitate AgBr, which was filtered, washed, and then dissolved in an ammoniacal solution of potassium tetracyanonickelate(II): Ni(CN)42- + 2AgBr(s) → 2Ag(CN)2- + Ni2+ + 2Br- The liberated nickel ion required 11.70 mL of 0.002146 M EDTA. Calculate mmol Ni in the 50.00 mL aliquot. Calculate mmol Br- in the 50.00 mL aliquot. Calculate the percentage of NaBr (102.894) in the 1.000 g sample.
A 1.000-g sample containing bromide was dissolved in sufficient water to give 100.0 mL. A 50.00 mL aliquot was measured and after acidification, silver nitrate was introduced to precipitate AgBr, which was filtered, washed, and then dissolved in an ammoniacal solution of potassium tetracyanonickelate(II): Ni(CN)42- + 2AgBr(s) → 2Ag(CN)2- + Ni2+ + 2Br- The liberated nickel ion required 11.70 mL of 0.002146 M EDTA The other 50.00 mL remaining solution was also analyzed for its Br- content by potentiometry using a metallic electrode of the second kind. Ecell recorded in running the solution using the potentiometric set-up was Ecell = 0.0286 V. (E0Ag/AgBr = 0.095 V) g) Compute for Eind. h) Compute pBr in the 50.00 mL aliquot. i) Compute for % NaBr ( in the potentiometric technique). j) Calculate the error between the obtained % NaBr fr the EDTA titration technique and the % NaBr from the potentiometric technique.