The amount of Fe (AW 55.85) in a 0.4891-g sample of an ore was determined by a redox titration with K2Cr2O7 (FW 294.20). The sample was dissolved in HCl and the iron brought into the +2 oxidation state using a Jones reductor. Titration to the diphenylamine sulfonic acid end point required 36.92 mL of 0.02153 M K2Cr2O7. Report the iron content of the ore as %w/w Fe2O3 (FW 159.70). a. 54.46 % b. 12.98 % c. 77.86 % d. 31.45 %

The amount of Fe (AW 55.85) in a 0.4891-g sample of an ore was determined by a redox titration with K2Cr2O7 (FW 294.20). The sample was dissolved in HCl and the iron brought into the +2 oxidation state using a Jones reductor. Titration to the diphenylamine sulfonic acid end point required 36.92 mL of 0.02153 M K2Cr2O7. Report the iron content of the ore as %w/w Fe2O3 (FW 159.70). a. 54.46 % b. 12.98 % c. 77.86 % d. 31.45 %

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

See similar textbooks

Similar questions

To analyze the amount of iron (Fe; Mw = 55.85 g/mol) contained in an ore sample, the sample was digested with acid and diluted to 50 mL with water. This solution was then treated with 25.00 mL of 0.2922 M EDTA. The excess EDTA was back titrated with 6.47 mL of 0.0843 M Zn2+ to reach the equivalence point. How many grams of Fe contained in the ore sample?
A cyanide solution with a volume of 13.72 mL was treated with 25.00 mL of Ni2+ solution(which contained an excess of Ni(II) ions) to convert the cyanide to the complex ion tetracyanonickelate(II): 4CN- + Ni2+ → 6 Ni(CN)2- The excess Ni 2+ was then titrated with 10.15 mL of 0.01307 M EDTA. One mole of this reagent reacts with one mole of Ni(II) as follows: Ni(CN)42- does not react with EDTA. If 39.35 mL of EDTA was required to react with 30.10 mL of the original Ni 2+ solution, calculate the molarity of CN- in the 13.72 mL cyanide sample.
A 0.7352g sample of ore containing Fe3+, Al3+ and Sr2+ was dissolved and made up to 500.00 mL. The analysis of metals was performed by a chemistry using complexation volumetry. Initially, an aliquot of 50.00 mL had its pH adjusted to 1.0 and titrated with a standard solution of EDTA 0.02145 mol/L, requiring 6.95 mL to reach the end point. Subsequently, another 25.00 mL aliquot was buffered at pH=5 and titrated with the same EDTA solution, requiring 6.24 mL to reach the end point. Finally, a third aliquot of 25.00 mL was titrated at pH=11, requiring 11.10 mL of the same EDTA solution to complete the titration. Determine the percentage of each of the metals in the sample Given the molar masses: Fe=55.845 g/mol; Al=26.982 g/mol and Sr=87.620 g/mol.
An alloy containing Ni, Fe and Cr was analyzed by a complexation titration using EDTA as titrant. A 0.7176 g sample of the alloy was dissolved in HNO3 and diluted to 250 mL in a flask. A 50.00 mL aliquot of the sample, treated with pyrophosphate to mask Fe and Cr, required 26.14 mL of 0.05831 M EDTA to reach the murexide endpoint. A second 50.00 mL aliquot was treated with hexamethylenetetramine to mask Cr and titration with 0.05831 M EDTA required 35.43 mL to reach the murexide endpoint. Finally, a third 50.00 mL aliquot was treated with 50.00 mL of 0.05831 M EDTA and titrated back to the murexide endpoint with 6.21 mL of 0.06316 M Cu(II). the weight percentages of Ni, Fe and Cr in the alloy.
A solution of sodium thiosulfate was standardized by dissolving 0.2450 g of KIO3 (214.00 g/mol) in water, adding a large excess of KI, and acidifying with HCl. The liberated I2 required 52.00 mL of the thiosulfate solution to decolorize the blue starch/iodine complex. Calculate the molarity of Na2S2O3
A 0.9352g sample of ore containing Fe³+, Al³+ and Sr²+ was dissolved and made up to 500.00 mL. The analysis of metals was performed using complexation volumetry. Initially, an aliquot of 50.00 mL had its pH adjusted to 1.0 and titrated with a standard 0.03145 mol/L EDTA solution, requiring 6.95 mL to reach the end point. Subsequently, another 25.00 mL aliquot was buffered at pH=5 and titrated with the same EDTA solution, requiring 6.24 mL to reach the end point. Finally, a third aliquot of 25.00 mL was titrated at pH=11, requiring 11.10 mL of the same EDTA solution to complete the titration. Given the molar masses: Fe=55.845 g/mol; Al-26.982 g/mol and Sr-87.620 g/mol. a) Determine the percentage of each of the metals in the sample. b) Explain why the change in pH allows the determination of the three ions in this sample.
0.7120 g of iron ore was dissolved and the iron was reduced to Fe2+ with Jones's reagent. Fe(II) was titrated with 0.02086 M KMnO4 and consumed 39.21 mL. What is the iron content of iron ore? Report the concentration as percentage of iron (Fe%) and iron oxide (Fe2O3%).
a 10 ml sample containing fe3+ and cu2+ was diluted to 100.0 mL solution. A 20 mL aliquot required 25 mL of 0.00500 M EDTA for complete titration. A separate 20 mL aliquot of the diluted sample was treated with NH4F to protect the Fe3+. Then the Cu2+ was treated with thiourea. Upon addition of 25.0 ml of 0.00500 M EDTA, the Fe3+ was liberated from its fluoride complex and formed an EDTA complex. The excess EDTA required 21.5 ml of 0.0180 M Pb2+ to reach an endpoint, using xylenol orange. (a) identify the masking agent (b) identify the auxiliary complexing agent (c) calculate the molar concentration of the fe3+ in the original sample (d) calculate the molar concentration of the cu2+ in the original sample
A 5.70 g iron ore was dissolved in concentrated HCL After the dissolution, the resulting solution was made basic by adding 6.0 M NaOH slowly until the solution is slightly turbid. Urea was then added and the solution was heated for 3 hours. The precipitate was filtered using an ashless filter paper and ignited to form Fe2O3 (159.69 L /mol The mass of precipitate is 2.1g. Find the % Fe3O4 (231.54 c/mol) in the iron are sample.
A cyanide solution with a volume of 10.33 mL was treated with 22.00 mL of Ni2+ solution (containing excess Ni2+) to convert the cyanide into tetracyanonickelate(II): 4CN−+Ni2+⟶Ni(CN)(2−)/4 The excess Ni2+ was then titrated with 11.85 mL of 0.01303 M ethylenediaminetetraacetic acid (EDTA): Ni2++EDTA4−⟶Ni(EDTA)2− Ni(CN)(2−)/4 does not react with EDTA. If 38.80 mL of EDTA were required to react with 30.47 mL of the original Ni2+ solution, calculate the molarity of CN− in the 10.33 mL cyanide sample. [CN-] = ________________________________M
When I was a boy, I watched Uncle Wilbur measure the iron content of runoff from his banana ranch. He acidified a 25.0-mL sample with HNO3 and treated it with excess KSCN to form a red complex. (KSCN itself is colorless.) He then diluted the solution to 100.0 mL and put it in a variablepathlength cell. For comparison, he treated a 10.0-mL reference sample of 6.80 3 1024 M Fe31 with HNO3 and KSCN and diluted it to 50.0 mL. The reference was placed in a cell with a 1.00-cm pathlength. Runoff had the same absorbance as the reference when the pathlength of the runoff cell was 2.48 cm. What was the concentration of iron in Uncle Wilbur’s runoff ?
Chromel is an alloy composed of nickel, iron and chromium. A 0.6553-g sample was dissolved and diluted to 250.0 mL. When a 50.00-mL aliquot of 0.05173 M EDTA was mixed with an equal volume of the diluted sample, all three ions were chelated, and a 5.34-mL back titration with 0.06139 M copper (II) was required.The chromium in a second 50.0-mL aliquot was masked through the addition of hexamethylenetetramine; titration of the Fe and Ni required 36.98 mL of 0.05173M EDTA. Iron and chromium were masked with pyrophosphate in a third 50.00-mL aliquot, and the nickel was titrated with 24.53 mL of the EDTA solution. Calculate the percentage of Cr in the alloy. Express your answer in 2 decimal places.

SEE MORE QUESTIONS

Recommended textbooks for you

Fundamentals Of Analytical Chemistry

Chemistry

ISBN:

9781285640686

Author:

Skoog

Publisher:

Cengage

General Chemistry - Standalone book (MindTap Cour…

Chemistry

ISBN:

9781305580343

Author:

Steven D. Gammon, Ebbing, Darrell Ebbing, Steven D., Darrell; Gammon, Darrell Ebbing; Steven D. Gammon, Darrell D.; Gammon, Ebbing; Steven D. Gammon; Darrell

Publisher:

Cengage Learning

Fundamentals Of Analytical Chemistry

Chemistry

ISBN:

9781285640686

Author:

Skoog

Publisher:

Cengage

General Chemistry - Standalone book (MindTap Cour…

Chemistry

ISBN:

9781305580343

Author:

Steven D. Gammon, Ebbing, Darrell Ebbing, Steven D., Darrell; Gammon, Darrell Ebbing; Steven D. Gammon, Darrell D.; Gammon, Ebbing; Steven D. Gammon; Darrell

Publisher:

Cengage Learning

SEE MORE TEXTBOOKS